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Goodman Furnace: The Ultimate Troubleshooting Guide

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No one enjoys coming home to a cold space in winter, especially if that isn’t because you’ve not installed a heating system but because your Goodman furnace is having issues.

While there are several issues with your Goodman furnace you can easily resolve by troubleshooting, a lot of others need the service of an HVAC pro or a trained electrician. 

This complete Goodman furnace troubleshooting guide gives you precise, step-by-step instructions on troubleshooting furnace issues and tells you which ones you should call a pro for and not try to resolve by yourself. 

If you are looking to troubleshoot or resolve a specific Goodman furnace issue, you can use the table of contents below to jump straight to it.

Goodman Furnace Won’t Turn On/Won’t Ignite

A Goodman furnace that’s not turning on(won’t ignite) has power or gas supply issues, restricted airflow, a bad thermostat, wrong ignition sequence, a dirty pilot light hole, or a dirty or defective flame sensor. Thermostat issues are the most common. Reset or replace the thermostat.

No Gas Supply

A gas furnace needs gas to ignite and run. If there’s no gas supply to your furnace or the gas supply is insufficient, your furnace won’t turn on even though the ignition light may be on.

A low gas supply or no supply at all could be caused by a closed gas supply valve or empty propane or LP tank.

How to diagnose lack of gas supply to your furnace

To make out why your furnace is not receiving gas, do the following:

  1. Check first if your furnace gas supply valve is open or closed. A closed furnace gas supply valve is at a quarter turn or perpendicular to the gas line. An open gas valve has the long side of the handle always parallel to the gas line.
  2. If your furnace uses gas from the municipal supply line, it will be hard to tell if the gas supply is cut. Try turning on another home appliance that’s served by the same gas line such as a cooker to test if it is receiving gas. 
  3. If you use a propane or LP gas tank, check the gas pressure gauge to tell if the tank still has fuel.

How to fix gas issues with your furnace

To fix your Goodman furnace gas supply issues, perform one of the following depending on the diagnosed cause:

  1. If your Goodman furnace’s low gas or no gas supply is caused by a closed gas supply valve, you need to open the valve by turning it in the anticlockwise direction until the long side of the handle is parallel to the gas line.
  2. If the issue seems to be with the natural gas supply line, call a professional HVAC technician or the municipal gas agency for your city to assess your natural gas supply line.
  3. If you have your own gas supply tank, check to ensure that there’s still fuel in the tank.

Power Supply Issues

A furnace that won’t ignite could simply not be powered. This could be because of a power switch that’s accidentally turned off, a tripped circuit breaker, or a faulty power control board.

How to diagnose Goodman furnace power supply issues

To find out what is causing a lack of power supply to your furnace:

  1. Check first if the furnace power switch is turned on.
  2. Open the circuit breaker box to see if it is tripped.
  3. Call in an HVAC expert or trained electrician to test the furnace power control board for faults. 

How to resolve Goodman furnace power issues

Power issues can be tricky to troubleshoot. The safest option is to call an expert electrician or HVAC expert to address the issue.

But, if you should feel up to the task, here are some troubleshooting tips to address furnace power issues:

  1. If the power switch is off – turn it on and check if that ignites your heating system.
  2. If the circuit breaker is tripped – open the panel and turn on the power back by pulling up the switch. If the switch is halfway on/off, push it down completely to turn it off then turn it back on by pushing it up. 

Call an HVAC expert or trained electrician to diagnose and resolve the cause of a circuit breaker switch that’s hard to turn or keeps tripping.

  1. If the power control board is faulty Call in an HVAC expert or trained electrician to replace a faulty furnace power control board. 

Poor Air Flow

Your Goodman furnace recirculates air from your home and through the outside vents. Proper airflow is key to keeping the burner running. If your furnace is located in a cramped room where there’s poor airflow, the air may be insufficient and the furnace won’t heat properly. Airflow to your furnace may also be compromised by these causes:

  • A dirty air filter.
  • An obstruction at the air inlet vents.
  • Closed dampers in the air ducts.
  • Clogged air ducts.
  • Insufficient return air vents.
  • Air duct leaks.
  • A broken air handler

How to diagnose poor airflow to your furnace

A Goodman furnace with poor airflow will:

  • Send minimal hot air or send cold air to your home because little is being supplied for heating. 
  • Show signs of overheating from overworking to supply sufficient air.
  •  Have a tripped rollout switch.

How to fix poor furnace airflow

Depending on the issue that is causing poor airflow to your furnace, one of the following troubleshooting options should be considered:

  1. If the air filter is dirty – Replace the air filter following these steps:
  1. Find the location of your Goodman furnace air filter. Depending on your Goodman furnace model, the filter may be located in the filter cabinet between the furnace and the return vent, in the blower compartment just before the air handler, or in the return vents inside the home.
  2. Remove the filter by pulling it towards you.
  3. Remove any dust around the filter housing by vacuuming it or using a damp cloth.
  4. Replace the filter with the new clean one by sliding it in the same position as the old filter.
  1. If there’s an obstruction at the air inlet – remove the obstruction to allow proper airflow into your furnace.
  2. If the dampers in the air ducts are closed – the opening and the closing process that regulates airflow will not function as they should. Adjust manual dampers using the lever on your duct system or call an electrician to repair any electrical errors that may have caused automatic dampers to get stuck.
  3. If the air ducts are clogged – call a furnace cleaning and maintenance service to unclog the ducts.
  4. If the return air vents are insufficient – Call a furnace expert to install adequate return air vents.
  5. If there are holes in the air ducts – the air will escape from the holes and not get to your furnace. Call an expert HVAC technician to repair the air ducts.
  6. A broken air handler – your furnace’s airflow will not be properly directed to the heat exchanger and ventilation. Call an HVAC service to inspect the air handler and repair or replace it as required.

 Thermostat Issues

A furnace thermostat regulates the heat produced by the furnace. If the thermostat is bad, the first consequence is that your furnace won’t turn on. There are several thermostat issues that can make your Goodman furnace not ignite;

  • Wrong thermostat settings – if the thermostat is not on the “Heat” settings.
  • Thermostat power supply – if there’s a power cut, a tripped circuit breaker, or a blown fuse.
  • Spent thermostat batteries – if your thermostat is battery-operated, spent batteries can cause the furnace not to start because the thermostat controls are not working.

How to diagnose Goodman furnace thermostat issues

First, check your furnace thermostat to see if it is set on the HEAT mode and not the COOL mode.

If the settings are ok, check the circuit breaker to see if it’s tripped and, if the thermostat uses a fuse, open the thermostat outer casing and locate the fuse. Check to see if the fuse is blown. A blown thermostat fuse will have a broken filament or the glass will appear stained. 

While your thermostat is open, test if the batteries are still charged. If you have AA/AAA batteries, the voltage should not be lower than 1.35 and if a 3V lithium battery, the charge should not be lower than 2.7/2.8 volts as that is considered a dead battery and needs to be replaced.

How to fix Goodman furnace thermostat issues

Depending on the issue affecting your Goodman furnace’s thermostat, you should perform one of the following: 

  1. Set your Goodman furnace thermostat to the HEAT mode if it’s on the COOL mode.
  2. Replace a blown thermostat fuse and turn back on a tripped circuit breaker switch. 
  3. If your thermostat uses batteries, replace dead batteries. Thermostat batteries usually last every couple of years and should be replaced after that. 

Wrong Ignition Sequence

If your Goodman furnace has been recently switched off for service or due to a blackout, you might need to reset it to follow a correct ignition and get it working again.

How to reset a Goodman Furnace that won’t turn on

Follow these steps to reset your Goodman furnace that won’t turn on:

  1. Turn off the power at the furnace’s main switch or at the circuit breaker.
  2. Turn off the external gas valve.
  3. Lower the temperature settings on the thermostat to the lowest it can go.
  4. Turn off the internal gas control knob.
  5. Let the furnace sit unpowered for five minutes.
  6. Turn the furnace back on, starting with the internal gas valve, the external gas valve, the electrical power switch, and finally reset the thermostat to the heating mode and the required temperature.

Your furnace should reboot and start working again.

Dirty Pilot Light Holes

If your Goodman furnace is an older model and uses a pilot light instead of an electronic ignitor, the furnace will not ignite if the pilot light has gone out. This is most likely caused by dirty pilot light holes.

How to diagnose dirty furnace pilot light holes

Look for these signs if you are suspecting that your furnace pilot light holes are dirty:

  • A diminishing pilot flame.
  • An orange/yellowish flame hue.
  • A furnace that won’t turn on.

How to fix dirty pilot light holes

To clean your Goodman furnace pilot light holes:

  1. Pick the holes with a fine wire or brush them with a stiff wire brush to remove any debris inside them.
  2. Turn on the furnace to see if the issue is resolved.
  3. Adjust the flame using the pilot light screw if cleaning the holes makes it too big. Your furnace pilot light should be stable and consistent at around 1½ and 2 inches and have a clean blue color.

If accumulated dirt in the pilot light holes is not resolved by this process, call in the service of an HVAC pro for comprehensive maintenance.

A Defective/Dirty Flame Sensor

A furnace flame sensor controls the burner by detecting the presence or absence of a flame. If the flame sensor is defective or dirty, it will not sense the flame and the ignition will not be confirmed. The control board will shut off power to the gas valve to prevent the furnace from overheating.

How to diagnose a defective/dirty furnace flame sensor

A dirty Goodman furnace flame sensor will be covered with soot or corrosion while a defective one will have cracks or missing pieces of the porcelain that covers the sensor rod. In addition, the bad flame sensor may keep clicking to try and sense the presence of a flame. 

To check for these signs of a dirty or defective furnace sensor, follow these steps:

  1. Switch off the furnace.
  2. Close the gas supply valve.
  3. Open the furnace and locate the flame sensor.
  4. Assess the flame sensor for soot and corroding or cracked/damaged sensor porcelain insulation.

How to fix a defective/dirty furnace flame sensor

If your Goodman furnace flame sensor is dirty, clean it following these steps:

  1. Shut off the power supply to the furnace.
  2. Remove the flame sensor by unscrewing it from its position.
  3. Use emery cloth, a fine abrasive, or light-grit sandpaper to remove dirt buildup from the flame sensor.
  4. Place back the flame sensor and turn on the furnace to see if it ignites.

If the flame sensor has cracked/damaged insulation, you need to replace it.

Note: Some furnaces have fixed flame sensors. Seek the services of a furnace repair company or an individual HVAC pro to assess, clean, and repair fixed flame sensors.

Goodman Furnace Won’t Shut Off

If your Goodman furnace won’t shut off, the power control board is bad, the limit switch is faulty, the thermostat settings are incorrect or the thermostat is faulty, or your home is poorly weatherized. Incorrect thermostat settings are most common. Simply set the thermostat correctly. 

Bad Power Control Board

A control board in a furnace regulates the voltage sent to each of the furnace parts. If the relay that regulates the voltage sent to the blower motor malfunctions, the blower motor will run continuously and your furnace won’t shut off.

How to diagnose a bad power control board

If you have some electrical knowledge, you can supply power directly to one of the furnace parts that appears not to be getting it from the power control board to confirm that it has malfunctioned. 

If that’s not the case, call in an HVAC pro or trained electrician to test the control board for faults.

How to fix a bad power control board

Fixing a bad power control board is a professional’s job reserved for trained HVAC technicians and not a DIY job. Call in an expert HVAC to confirm that your furnace’s control board is faulty and replace it with the correct one for your Goodman furnace model. 

A Faulty Limit Switch

A limit switch is located under the furnace’s hood and has the function of telling the furnace’s blower when to go on and when to turn off. Most Goodman furnaces have multiple limit switches for safe operation. The primary limit switch stops your furnace from overheating and is programmed to automatically reset if it should malfunction. If this does not happen, however, your furnace could keep running nonstop. 

How to test and fix a faulty Goodman furnace limit switch

In most cases, a malfunctioned limit switch will have to be replaced. Follow these steps to test the limit switch for continuity and replace a faulty one:

  1. Shut off the power supply to the furnace and close the gas valve.
  2. Remove the outer cover panel using the push or twist lock, a screwdriver, or socket wrench depending on your model.
  3. Locate the limit switch on the side of your furnace’s housing and remove the connecting wires. Unscrew to remove the limit switch.
  4. Use a multimeter that’s set to the lowest Ohms of resistance.
  5. Touch the probes of each terminal on the limit switch to test for continuity. If the limit switch has continuity, the multimeter will be reading 0 Ohms. If the limit switch is faulty, the multimeter will show infinite resistance and the limit switch needs to be replaced.
  6. Place the new limit switch in the position of the old one and screw it into place.
  7. Reconnect the wires.
  8. Replace the outer cover.
  9. Open the gas valve and turn the power back on. Your furnace should resume running normally.

Call an HVAC expert to replace a faulty furnace limit switch if you do not feel up to the task.

Incorrect Thermostat Settings

During the heating season, your Goodman furnace thermostat should be set to the HEAT mode and with a required temperature range (between 68°F-72°F [20°C-22°C]) when awake or in the house and (between 62°F-66°F [17°C-19°C]) when away or asleep. In addition, the fan should be set to AUTO so it only runs when the heating cycle is on.

If your thermostat is set too high from the room temperature, the furnace will keep going to try and obtain the room temperature. Also, if the fan is set to ON, it will keep going even though the furnace is not heating your home.

How to fix incorrect thermostat settings

If what keeps your furnace continuously on is a thermostat in the HEAT mode and a temperature that’s set too high, lower the temperature closer to the room temperature. For example, if the thermostat in the HEAT mode is set at 72°F and the room temperature is 68°F, lower the temperature to 66°F.

If, instead, the issue is wrong fan settings (the fan is set at ON and runs perpetually), change the fan settings to AUTO.

A Faulty Thermostat

The thermostat has electrical connections that control the cycles of the furnace. If the thermostat is faulty and does not control the supply of data to the furnace, or the connection that controls the commands to the blower motor is closed, voltage is continuously sent to the blower motor causing it to run continuously. 

How to detect and fix a faulty thermostat

Use a multimeter to test the thermostat for continuity while it is in the off position. If the thermostat shows continuity between the terminals, it is faulty and needs replacement. 

Call in an HVAC pro or a trained electrician to replace the faulty thermostat as it requires some electrical knowledge. 

Poor Home Weatherization

Weatherization is a move to weatherproof the interior of a building from the elements to reduce energy consumption and promote energy efficiency. This can be done by insulating walls, ceilings, doors, windows, as well as spaces around ducts and water heaters among others. 

If your home is poorly weatherized, cold air will find its way inside and hot air will escape to the outside. This will cause the furnace to keep running to supply the required hot air.

How to fix poor home weatherization

Simply ensure that the doors, windows, walls, and ceilings are well insulated so warm air does not escape out of the home or cold air find its way into the home. 

Consider using the easy-to-fix Duck Brand Indoor 10-Window Shrink Film Insulator Kit from Amazon for your windows if they are letting in cold air and allowing hot air to escape. This clear shrink film will seal off drafts and air leaks without tampering with visibility. What’s more, it is easy to peel off once the cold season is gone without leaving marks, plus it’s quite affordable.

If your doors are letting in cold air and losing hot air, consider Suptikes Door Draft Stopper to stop any incoming cold air or outgoing hot air. This self-adhesive door draft blocker is especially perfect for doors with extra-large gaps. You can easily measure the size of the open space below your door and cut the excess seal to fit. If your door has a smaller gap, consider the Holikme Twin Door Draft Stopper which has a hook-and-loop fixation to prevent the draft stopper from moving when the door is opened or closed. You can also choose from a variety of colors to fit your home color theme.

Goodman Furnace Won’t Stay Lit/Keeps Shutting Off

If your Goodman furnace won’t stay lit or keeps shutting off, the flame sensor is dirty, the limit switch is defective, the pressure switch is faulty, the inducer motor is bad, the air filter is dirty, the thermostat is faulty (most common cause), or the control board has malfunctioned.

Dirty Flame Sensor

The flame sensor is attached to one of the burners and detects the presence of a flame in your furnace. If it’s covered with dirt, it will not detect the flame and will act as though no flame is present, thereby shutting off the gas control to prevent it from filling the furnace area. As a result, your furnace will keep shutting off every time you try to light it and won’t stay lit. To resolve the issue, you need to clean the flame sensor.

How to clean a dirty flame sensor

If your Goodman furnace flame sensor is dirty, follow these DIY steps to clean it:

  1. Shut off the power supply to the furnace.
  2. Unscrew the flame sensor to remove it from its position.
  3. Rub the flame sensor with light-grit sandpaper, an emery cloth, or a fine abrasive to clean the dirt on its surface.
  4. Replace the flame sensor back into its position and screw it on.
  5. Turn on the furnace to see if it resumes normal heating. 

You can watch these steps here.

If cleaning the flame sensor does not resolve the issue and other possible causes have been eliminated, the flame sensor is defective and should be replaced. If your manual does not give details on the type of flame sensor you should purchase, talk to a Goodman dealer near you or contact Goodman Customer Support to get the right flame sensor for your model.

Defective Limit Switch

The limit switch is a sensor that’s attached to the mounting plate and has the function of reading the temperature around the burners. If it should happen that the inducer fan motor is not drawing enough air to the burners or the furnace isn’t venting as it should leading to overheating, the limit switch opens to stop the ignition sequence and preempt overheating. This causes the furnace to shut off after a few minutes. This can also happen if your furnace’s limit switch is defective and so incorrect in reading the temperature around the burners.

How to test and fix a defective limit switch

The best way to keep your furnace’s limit switch working properly is to ensure consistent airflow to your heating unit. This is especially ensured by a clean air filter and a properly working inducer motor. 

If, instead, the limit switch seems defective, test it for continuity and replace it. Read details on how to test and fix a defective limit switch in the section on “Goodman Furnace Won’t Shut Off.”

A Bad Pressure Switch

The pressure switch(es) is an open switch in a Goodman Furnace that monitors airflow and closes when the inducer motor starts to run and the correct pressure levels are obtained. This allows the current to go through to complete the furnace ignition process. 

A bad pressure switch will stay open even when the required air pressure is obtained. This stalls your furnace’s ignition process, causing it to shut off. 

How to diagnose a bad Goodman furnace pressure switch

To test if your Goodman furnace pressure switch is bad, follow these steps:

  1. Disconnect power to the pressure switch by detaching the wires.
  2. Set the multimeter to resistance (Ohms).
  3. Touch the limit switch with the probes of the multimeter. If there’s continuity (multimeter shows infinite resistance), the pressure switch is stuck open, which means it is a bad switch that’s not doing its work. (If you use the voltage part of the multimeter, the pressure switch should show 27volts when open and 0 volts when closed).

How to fix a bad Goodman furnace pressure switch

To change a bad furnace pressure switch, follow these steps:

  1. Switch off the furnace. 
  2. Remove the furnace’s outer cover.
  3. Locate the pressure switch and detach the connection wires.
  4. Unscrew the pressure switch and pull it out.
  5. Slide the new pressure switch onto the location of the old one and screw it into place.
  6. Reattach the connection wires to the new pressure switch.
  7. Replace the outer cover and switch the furnace back on. The ignition process of your furnace should now run smoothly and start heating without a hitch.

A Defective Inducer Motor

When your furnace is turned on, the draft inducer motor begins to run to draw air into the heating chamber. Consequently, the pressure switch detects the correct pressure levels and closes to alert the control board that the furnace has correct airflow and the ignition process should proceed.

If the draft inducer motor is defective, the pressure switch won’t close and the ignition process will be halted, causing the furnace to shut off a few minutes after it’s switched on.

How to diagnose a defective Goodman furnace inducer motor

A defective furnace inducer motor needs to be replaced. Before doing so, it’s important to test the inducer motor to confirm that it’s really defective. Follow these steps:

  1. Turn off the power supply to the furnace. You can and use a voltage pen to ensure no voltage is running into the furnace before proceeding further. A non-contact voltage pen like the Neoteck Non-Contact AC Voltage Tester Pen is advised as it does not require electrical knowledge and does not expose you to shock.
  2. Remove the outer cover of the furnace.
  3. Reach out to the inducer motor, usually situated to the upper right of the furnace, and place your hand close to it to see if it is hot (do not touch if you detect heat when you bring your hand to the motor as it could burn). A hot inducer motor is an indication it’s been trying to run unsuccessfully, which suggests it’s defective.
  4. Reach out to the squirrel cage on the left. (A squirrel cage in a furnace is an AC induction motor that’s connected to the motor to make it run). Turn the squirrel cage with your hand, staying alert not to hurt your hand with the sharp fins. If the squirrel cage does not spin freely, it is a sign the draft inducer motor is defective and needs to be replaced. 

How to fix a defective Goodman furnace inducer motor

As will be seen from the process, replacing a defective furnace inducer motor is a long and complex process. As such, we recommend that you call a trained HVAC technician to replace a defective furnace inducer motor as it requires plenty of dismantling and handling of wires. 

However, if you feel up to the task, follow these steps to replace a defective Goodman furnace inducer motor: 

  1. Turn off the power supply to the furnace and close the gas valve.
  2. Remove the outer covering of the furnace.
  3. Locate your furnace draft inducer motor on the upper right side of the furnace.
  4. Remove the pressure switch hoses of the inducer motor. 
  5. Remove the connection wires of the pressure switch(es).
  6. Loosen the clamp and slide the hose pipe up to remove it.
  7. Disconnect the grounding wire (usually green) and the draft inducer motor connection wires.
  8. Remove the mounting screws and pull out the inducer motor.
  9. Align the new motor in the position of the old one and tightened the mounting screws back.
  10. Put back the motor connecting wires and secure back the grounding wire.
  11. Slide the exhaust pipe back and secure the cramp.
  12. Place back the pressure switch(es), screw them back firmly and, reconnect the wires.
  13. Reattach the pressure switch hoses.
  14. Replace the outer cover.
  15. Open the gas valve and switch on the furnace power supply. Your furnace should resume working normally.

A Malfunctioned Power Control Board

A furnace power control board monitors the supply of power to the components of your heating system. If the control board malfunctions, it will not sustain voltage supply to the furnace ignition parts and the furnace will shut off as soon as it fires up. 

How to test and fix a bad Goodman furnace power control board

A power control board is made up of many electrical wires and connections. We advise you don’t try troubleshooting a bad control board. Call a trained electrician or HVAC pro to test the control board for faults and repair/replace it as required.

A Dirty and Clogged Air Filter (Restricted Air Flow)

A dirty and clogged Goodman furnace air filter restricts air filtration and obstructs the flow of air into the heat exchanger. This can cause the heat exchanger to become too hot from poor airflow and, as a safety mechanism, the furnace shuts down. 

Depending on whether you have a washable or disposable furnace air filter, a clogged air filter should be washed or replaced as the case requires.

How to diagnose a dirty and clogged Goodman furnace air filter

To check whether your Goodman furnace air filter is dirty:

  1. Shut off the power supply.
  2. Locate the filter at the side of the furnace.
  3. Remove the access door by pulling it towards you. This will reveal the air filter.
  4. Gently pull out the air filter and check if it’s covered with dirt, then proceed to clean/change it as the case requires.

How to clean a dirty and clogged Goodman furnace air filter

If your Goodman furnace air filter is washable, follow these steps to clean it:

  1. Shut off the power to your Goodman furnace.
  2. Locate the filter, usually at the side of your Goodman furnace.
  3. Pull the access door towards you to open and reveal the filter.
  4. Remove the dirty filter by gently sliding it out from its housing.
  5. Use a low-pressure hose to clean the air filter with water until the water dripping from the filter is clear.
  6. Leave the filter under the shade to dry.
  7. Replace the filter back into the furnace once completely dry.
  8. Close the access door and turn the furnace back on.

If your Goodman furnace air filter is disposable, follow these steps to change it;

  1. Shut off the power to your Goodman furnace.
  2. Locate the filter, usually at the side of your Goodman furnace.
  3. Pull the access door towards you to open and reveal the filter.
  4. Remove the dirty filter by gently pulling it out from the unit and dispose it off.
  5. Use a vacuum to remove any dust from the filter housing.
  6. Slide in the new filter in the same position as the old one just removed.
  7. Close the access door and turn the furnace back on.

Note: Airflow to your furnace’s heat exchanger can also be restricted by closed vents. Ensure that the vents are open to allow an ample amount of air to flow into your furnace.

A Malfunctioned Thermostat

The thermostat regulates the cycles of a furnace by indicating when it should turn on and when to shut off according to the temperature range. 

If your thermostat is malfunctioned and not communicating with the furnace to send the command to heat, the furnace will have no data to work with and will shut off as soon as it’s turned on.

How to diagnose a malfunctioned furnace thermostat

Use a multimeter to test the thermostat for continuity while it is in the off position. If the thermostat shows continuity between the terminals by presenting a 0 Ohms reading, it is faulty and needs replacement. 

How to replace a malfunctioned furnace thermostat

Replacing a thermostat requires some electrical knowledge. Call in a trained electrician or an HVAC expert to replace the faulty thermostat.

Goodman Furnace Won’t Ignite, 1 Blink (Goodman Furnace 1 Blink Error Code)

If your Goodman furnace won’t ignite and there’s 1 blink, the furnace has locked out due to multiple (3) ignition trials. This can be caused by the failure to establish a flame or the loss of the flame once it is detected.

Failure to Establish a Flame

If your Goodman furnace does not establish a flame, it could be due to one of these reasons: 

  • There is no gas running to the burners.
  • The pressure switch is stuck open.
  • There’s a bad ignitor or ignitor is badly aligned.
  • The orifices are improper or blocked.
  • The flame sensor is coated with soot or improperly connected.

How to fix Goodman furnace not establishing flame

If your Goodman furnace is not establishing flame, call an HVAC expert or troubleshoot with one of these options depending on the cause:

  1. Locate the source of gas interruption and correct it.
  2. Assess the pressure switch operation and correct any issues related to the pressure switch hoses, wiring, or contact operation.
  3. Replace or realign ignitor.
  4. Check the flame sensor signal and clean the flame sensor if it is coated with soot, rust, or other forms of debris.

Loss of Flame after it’s Established

If your Goodman furnace establishes a flame but the flame is lost, the cause could be one of the following:

  • Interrupted gas supply.
  • Improper/restricted gas pressure at the burners.
  • The pressure switch opening after it had closed.
  • Poor functioning of the induced draft blower. 

How to fix Goodman furnace losing flame after it’s established

If your Goodman furnace loses the flame after it had been established, call an HVAC pro or troubleshoot with one of these options depending on the problem:

  1. Assess the flue piping for blockage, restricted size, elbows, and termination.
  2. Address any issues with the gas supply.
  3. Test the pressure switch for malfunction and replace it if faulty.
  4. Test the draft inducer motor for faults and repair or replace if required.

Goodman Furnace not Heating/Not Blowing Hot Air

If your Goodman furnace is running but not heating (not blowing hot air), the thermostat settings are incorrect or thermostat is defective, the filter is clogged, the furnace is undersized, or your home is poorly weatherized. Incorrect thermostat settings are the most common. Simply correct them. 

Incorrect Thermostat Setting and Thermostat Issues

The thermostat controls the heating patterns in your furnace. If the thermostat has incorrect settings, it will send erroneous data to the furnace. In the case where the furnace is not heating or not blowing hot air, the furnace settings may be set on COOL instead of HEAT, or the set temperature in the HEAT mode is set too low (too close to the room temperature).

How to diagnose incorrect settings on a furnace thermostat

Check the data on your furnace thermostat to see if the settings are on the COOL or HEAT mode. Also, check if the set temperature is below the room temperature or too close above the room temperature.

How to fix incorrect furnace thermostat settings

If your furnace thermostat is set on the COOL mode, set it on the HEAT mode and then proceed to set the desired set temperature. The set temperature should be at least 3-5 points higher than the room temperature.

If your thermostat settings are correct but its sending wrong data to the furnace, causing it not to heat, check it for these issues:

  1. Check and ensure that your thermostat’s program is displaying the correct date and time.
  2. Check the wires connecting the thermostat to the furnace for breaks or loose connections.
  3. Test the thermostat batteries to ensure they are not dead or have low voltage and replace them if required. Dead thermostat batteries will cause your thermostat to lose all the programmed data in case of a power outage.
  4. Remove any dust or debris covering the thermostat by opening the thermostat’s outer casing a gently blowing out the dust.

If your furnace still won’t heat, consider one of the other causes discussed below.

Dirty Air Filter

A clogged air filter allows little air into your furnace. That means your furnace will be working with limited air. The limited hot air may barely make it through the vents to your home, which might feel like there’s no hot air blowing from the furnace. 

Limited air due to a dirty air filter can also cause other parts of the furnace to malfunction or stop running, explaining why your furnace will not be heating.

How to diagnose a dirty furnace air filter

Your Goodman air filter is usually located at the side of the furnace. To check whether the air filter is dirty:

  1. Locate the filter.
  2. Shut off the power supply.
  3. Remove the access door by pulling it towards you. This will reveal the air filter.
  4. Gently pull out the air filter and check if it’s covered with dirt, then proceed to clean/change it as the case requires.

How to clean a clogged furnace air filter

A Goodman furnace air filters should be checked every 30 days and changed or cleaned every 3 months. You can keep a record of the air filter changing time using an air filter subscription program such as Subscribe & Save from Amazon.

Depending on whether you have a disposable or washable air filter, follow the steps below to fix your dirty Goodman air filter.

To replace your dirty Goodman furnace air filter:

  1. Shut off the power to your Goodman furnace.
  2. Locate the filter, usually at the side of your Goodman furnace.
  3. Pull the access door towards you to open and reveal the filter.
  4. Remove the dirty filter by gently pulling it out from the unit and dispose it off.
  5. Use a vacuum to remove any dust from the filter housing.
  6. Slide in the new filter in the same position as the old one just removed.
  7. Close the access door and turn the furnace back on.

To clean your washable Goodman furnace air filter:

  1. Use a low-pressure hose to clean the air filter with water until the water dripping from the filter is clear.
  2. Leave the filter under the shade to dry.
  3. Replace the filter back into the furnace once completely dry.
  4. Close the access door and turn the furnace back on.

An Undersized Furnace

If you’ve just installed your Goodman furnace and it appears it’s not heating (not blowing hot air), the furnace may be too small for your home space. This means that the hot air sent by the furnace to your home is not meeting the heating need of the space, making it appear as though it’s not blowing hot air. As a consequence, the furnace will be running for longer heating cycles, which will, in turn, increase your power bills.

How to diagnose an undersized Goodman furnace

Calculate the space size of your home in square feet by multiplying its width and length and checking the BTU rating of your Goodman furnace filter. Then find out if your Goodman furnace’s BTU rating is the right size for the space as explained below. 

How to fix an undersized Goodman furnace

Unless you want to keep freezing for the rest of the winter season, the best way to fix an undersized Goodman furnace is to replace it with the correct size.

To do this, consider the home space size you calculated in square feet and the recommended heating factor for your zone. The recommended heating factors for the different zones are as follows:

Heating ZoneHeating BTUs / Sq. Ft.
Climate Zone 130-35 BTUs / sq. ft.
Climate Zone 235-40 BTUs / sq. ft.
Climate Zone 3 40-45 BTUs / sq. ft.
Climate Zone 445-50 BTUs / sq. ft.
Climate Zone 550-60 BTUs / sq. ft. (you may find 50-55 BTUs / sq. ft. in some sources)
NB: For climate Zone 6 & 7 – a citation is needed. 

So, assuming you live in Coastal California which is in Zone 2 and your home is 3,000 sq. ft., then you’ll need a furnace with a BTU rating between 105,000 and 120,000.

Poor Home Weatherization

If your home is poorly weather-proofed so that the heat from your furnace is lost to the outside and cold air comes in through air outlets on your doors, windows, ceilings, or air ducts, then you might feel like your furnace is not heating. In this case, your furnace is not the problem, but the poor insulation of your home is to blame. And, as can be guessed, your furnace will need to stay on for longer cycles to make up for lost hot air, augmenting your energy bills.

How to diagnose poor home weatherization

Assess your home insulation by checking for any air outlets on doors, windows, ceiling, and leaks on ducts.

How to fix poor home weatherization

Make sure your home doors, windows, walls, and ceilings are well insulated. You can use temporary insulation fixes like the earlier discussed easy-to-fix Duck Brand Indoor 10-Window Shrink Film Insulator Kit to seal your windows and stop hot air from escaping to the outside or cold air from entering inside your home. The earlier mentioned Suptikes Door Draft Stopper and Holikme Twin Door Draft Stopper are also optimal options to seal your doors. 

Goodman Furnace Burners Won’t Light

If your Goodman furnace burners won’t light, the gas supply is cut or the furnace gas supply valve is closed, the pressure switch is faulty and is stopping the ignition process, or the gas burners are dirty. Dirty gas burners are a more common cause. Clean the burners to allow proper gas flow.

No Gas Supply

Your Goodman furnace needs gas to ignite the burners. If the gas supply is cut due to lack of gas or a closed gas valve, the burners won’t be turning on.

How to diagnose lack of gas supply to a furnace

If you have other home equipment running on gas such as the cooker, test to see if they are working. If they are, then your furnace gas supply is not the problem and it could be that the gas valve is closed.

How to fix a closed Goodman furnace gas valve

To open your Goodman furnace gas supply valve:

  1. Locate the gas supply valve beside or at the back of the furnace.
  2. A gas valve that is perpendicular or at a quarter turn to the gas line is closed. To open it, rotate the valve in a counterclockwise direction so that the long side of the handle is parallel to the gas line. 

If your gas line is supplying gas and the gas supply valve is open and the burners will still not ignite, call an HVAC expert to check your furnace. It is dangerous to try to resolve furnace gas issues if you are not sure what the problem is exactly. Keep the furnace turned off while you wait for professional help. Also, if your furnace uses a propane or LP gas tank, check to ensure that the tank still has fuel.

Bad Pressure Switch

The pressure switch monitors air pressure when the furnace is turned on and the inducer motor starts to run. Once the pressure switch detects the required air pressure, it closes to allow the ignition process to be completed with the lighting of the burners. If the pressure switch is bad, it will not close when required to, thereby halting the ignition process, and the burners won’t turn on. 

How to diagnose a bad Goodman furnace pressure switch

To check if your Goodman furnace pressure switch is bad, test it for resistance following these steps:

  1. Turn off the power to the furnace and detach the pressure switch connection wires.
  2. Set the multimeter to resistance (Ohms).
  3. Touch the limit switch with the probes of the multimeter. If the multimeter records 0 resistance, the issue may be with other parts. But, if it records infinite resistance, it shows continuity while there’s no voltage running into it and that means the pressure switch is stuck open or it’s bad and not working properly. A bad pressure switch needs to be replaced with a new one.

How to change a bad Goodman furnace pressure switch

To change a faulty pressure switch and replace it with a functional one, follow these steps:

  1. Turn off the furnace power switch. 
  2. Remove the furnace’s outer cover.
  3. Find the pressure switch and remove the connection wires.
  4. Remove the screws holding the pressure switch or the furnace and pull it out.
  5. Place the new pressure switch where the old one was removed and screw it into place.
  6. Reconnect the wires.
  7. Place back the outer cover of the furnace and turn on the power switch. The ignition process of your furnace should start running smoothly until the burners are ignited.

Dirty Gas Burners

To allow a clear flow of gas, your Goodman furnace burners should be clean and clear of any dirt. Dirty furnace burners also compromise the amount of oxygen that circulates around the burners to keep them lit. If you have dirty burners, chances are they won’t light.

How to check Goodman furnace gas burners for dirt

Poorly lit or non-lighting burners could easily be a sign that they are dirty. To confirm it though, you’ll need to:

  1. Switch of the furnace.
  2. Remove any connection wires on the way of the furnace burners. Mark the wires and ports to ensure you replace them in their right place once done.
  3. Unscrew the burners then lift them one after the other to unhook and remove.
  4. Check if the burners’ holes and channels are covered with dirt and proceed to clean them if that is the case.

How to clean dirty Goodman furnace gas burners

Considering that you had removed your furnace burners to check them for dirt, proceed with these steps to clean them:

  1. Use a wire brush to remove any dirt in the gas channels and burner holes. You can use a vacuum to clear any loose dirt after scrubbing with the wire brush.
  2. Replace the burners, making sure they fit back into the hooks, then screw them back in their place.
  3. Reattach the connection wires back to their ports.
  4. Switch the furnace back on to start heating your home.

Goodman Furnace Fan Won’t Turn On

If your Goodman fan is not working, the control board has malfunctioned, the blower motor is damaged or the capacitor is bad. A bad capacitor is a more common cause and should be replaced.

A Malfunctioned Control Board

When the burners of your Goodman furnace ignite, the heating cycle proceeds to run the fan blower. This usually happens 60-90 seconds after the burners light up and is controlled by an internal timing of the control board. If the control board malfunctions, the internally programmed timing will not take effect and the fan will not run.

How to diagnose a bad control board causing fan issues

To make out if the control board is causing a hitch in the running of the fan, set the fan on the ON option on the thermostat. This option causes the furnace fan to run continuously. If the fan runs, then the fan motor is not the issue and the control board should be examined.

How to fix a bad control board causing fan issues

Because the control board is all about electrical connections, you should call a professional electrician or HVAC expert to assess the control board for faults and repair or replace it as required.

Damaged Blower Motor

A Goodman blower motor spins the fan so it can blow the heated air through the ducts and vents into your home. If it is damaged it will not run or will run inefficiently. 

Because it is in continuous motion, the blower motor is susceptible to wear. But your Goodman furnace blower motor can also malfunction due to overheating, dust and debris buildup, or exposure to excessive moisture, especially if your furnace is installed in a damp area of the home. All these factors can cause the bearings and windings of the blower motor to wear faster.

How to diagnose a damaged blower motor

There are several signs that will indicate your Goodman blower motor has issues:

  • Poor airflow through the vents into your home or no air coming through.
  • Humming noise when the furnace is turned on.
  • Overheating and a smell of burning.
  • Inflated energy bills.

How to fix a damaged blower motor

A bad blower motor is best serviced and replaced by a trained HVAC expert. To replace a bad Goodman furnace blower motor, the HVAC pro will have to check the right information about the blower motor including the type of drive, the rotation direction, the horsepower, the size of the capacitor, the speeds and voltage, and the diameter of the motor.

Bad Capacitor

A capacitor is a connected part of a furnace fan motor that provides electricity to start and run the furnace parts. This is why capacitors are described as start/run capacitors.

If your Goodman furnace capacitor is bad, the fan motor may try to start without success and usually make a loud humming sound. If it starts, it might run and hum for a few seconds and then stop automatically.

How to diagnose a bad furnace capacitor

A bad furnace capacitor will come with these signs;

  • Loud humming sounds when the furnace is switched on and the fan tries to run.
  • A fan blower motor that does not run.
  • Abnormal or erratic blower motor operation due to inconsistent power supply.

You can also test the capacitor using a multimeter that also reads Micro Farads. If your capacitor records a lower number of Micro Farads than what it is rated for, then it is bad.

How to fix a bad furnace capacitor

Because a capacitor is an electrical part that requires some basic knowledge, we recommend you call a trained electrician or HVAC pro to test and repair a bad furnace capacitor.

However, if you should decide to go DIY, here are the troubleshooting steps:

  1. Turn off the power supply to the furnace.
  2. Locate the furnace capacitor just next to the blower motor.
  3. Check your furnace capacitor to read the voltage and Micro Farads. (Capacitors are rated with voltage and Micro Farads).
  4. Order/purchase a similar capacitor to replace the old one.
  5. Notice the wiring positions to ensure you replace them back accordingly once done. You can take pictures for reference.
  6. Once you have the new capacitor, disconnect the capacitor wiring.
  7. Remove any screws or bolts holding the capacitor in its place.
  8. Remove the capacitor.
  9. Place the new capacitor in place of the old and screw/bolt it in place.
  10. Reconnect the capacitor wiring.
  11. Switch the furnace power back on and test the working of the blower motor and fan.

Goodman Furnace Keeps Short Cycling

If your Goodman furnace is short cycling, the thermostat’s set temperature may be too low, the furnace may be oversized, or the furnace may be overheating due to restricted airflow. Restricted airflow from a dirty air filter is a common cause that should be resolved by washing/replacing the filter.

Incorrect Thermostat Settings

The thermostat tells your furnace when to turn on and heat and when to stop. This process constitutes the heating cycles that go for 10-15 minutes.

If your furnace is running for shorter cycles than this, the set temperature in the HEAT mode may be too low (too close to the room temperature), so that the heater quickly achieves the set temperature and the thermostat sends the ‘stop heating’ signal just as fast.

How to diagnose incorrect furnace thermostat settings

Check your thermostat to determine if the set temperature is set too close to the room temperature. For example, if the room temperature is at 66°F (18.8°C) and the thermostat is set at 68°F (20°C), the heater will be cycling often.

How to fix incorrect furnace thermostat setting

If your Goodman furnace is short cycling due to a low set temperature, set the temperature level a few degrees upwards. The recommended temperature setting for your Goodman furnace during the heating season is between 68°F-72°F (20°C-22°C) when awake in the house and between 62°F-66°F (17°C-19°C) when away or asleep.

Note that a malfunctioning thermostat can also send the signal that the required temperature has been reached and cause the furnace to shut off prematurely. Call in an HVAC pro to replace a malfunctioning thermostat.

An Oversized Furnace

Especially if your Goodman Air conditioner is new, it might be short cycling because its BTU rating is higher than what is required for the space you are heating. If this is the case, your Goodman furnace will heat the room quickly and the thermostat will send the signal that the required temperature has been attained. However, the hot air will be poorly distributed in the room and the thermostat will detect low temperatures sooner than it should, which makes your furnace keep running in short cycles.

How to diagnose an oversized Goodman furnace

You can tell if your Goodman furnace is oversized by calculating the size of your home in square feet and checking if the BTU rating of the furnace is right for the space. 

How to fix an oversized Goodman furnace

The most reliable way of fixing an oversized Goodman furnace is by replacing it with one that’s the correct size for the space.

Goodman Air Conditioning and Heating advises that, when considering the size of your heating unit, you should bear in mind a number of factors such as your home’s ceiling height, the type of construction, and window size and placement. 

But, as a starting point, you should calculate the size of the furnace that you require for your home by multiplying your home’s size in square footage by the recommended heating factor. Recommended heating factors are given in zones as follows:

Heating ZoneHeating BTUs / Sq. Ft.
Climate Zone 130-35 BTUs / sq. ft.
Climate Zone 235-40 BTUs / sq. ft.
Climate Zone 3 40-45 BTUs / sq. ft.
Climate Zone 445-50 BTUs / sq. ft.
Climate Zone 550-60 BTUs / sq. ft. (you may find 50-55 BTUs / sq. ft. in some sources)
NB: For climate Zone 6 & 7 – a citation is needed. 

For example, if you live in Houston which is in Zone 1 and your home is 1500 sq. ft., then you’ll need a furnace with a BTU rating between 45,000 and 52,500.

An Overheating Furnace

As an auto protection mechanism, your Goodman furnace will turn off if the temperature in the furnace is too high. Overheating is usually caused by restricted airflow, making hot air to be trapped in the furnace.

There are several causes of restricted airflow in a furnace including:

  • A dirty air filter
  • Undersized return air vents
  • Leaks in the air ducts
  • A blocked air inlet.
  • Clogged air ducts.

How to diagnose an overheating Goodman furnace

Short cycling is one of the key signs of an overheating furnace. Other signs to look out for include a burning smell from the vents and unusual noises such as loud furnace humming.

How to fix an overheating Goodman furnace

You should immediately shut off a furnace that is overheating and address the cause:

  1. Clean a dirty furnace air filter.
  2. Unblock clogged air inlet vents or air ducts.
  3. Replace undersized air vents with the right size.
  4. Repair leaks in the air ducts.

Call an HVAC expert to resolve furnace overheating issues if you are not sure of the cause and how to resolve it.

Goodman Furnace Not Cooling

A Goodman furnace that is not cooling (blowing cold air) is working in its normal process as long as it is blowing hot air. If your Goodman furnace is blowing cold air, this is considered a malfunction caused by incorrect thermostat settings, dirty air filters, or leaky ductwork among other issues. (Read about Goodman furnace blowing cold air later in the article).

So, unless you have a Goodman reverse heating system, commonly known as a heat pump, your ordinary Goodman furnace should not be sending cool air to your home under normal circumstances. 

Generally, a Goodman reverse heating system works by:

  • Pulling heat from the outside air in the cold months and transferring it to your home.
  • Pulling warm air and humidity from your home during the warmer months and transferring it outside, thereby leaving the air indoors cooler.

You can read more about Goodman reverse heating systems here.

Goodman Furnace Not Blowing Air

If your Goodman furnace is running but not blowing air, the furnace fan has issues caused by a bad limit switch or a malfunctioned blower motor. Alternatively, the air ducts are blocked and need to be opened. A bad blower motor is a more common cause and should be replaced by an HVAC technician.

A Malfunctioned Limit Switch

A limit switch directs the furnace’s blower to go on or turn off. While the limit switch is programmed to automatically reset if it should malfunction, it could malfunction completely and cause the blower motor not to run and distribute hot air to your home. 

How to diagnose and fix a malfunctioned Goodman furnace limit switch

To test if your Goodman furnace has a malfunctioned limit switch, follow these steps:

  1. Turn off power to the furnace.
  2. Remove the outer cover panel of the furnace.
  3. Locate the limit switch on the side of your furnaces housing and disconnect the wires.
  4. Remove the screw to take out the limit switch.
  5. Using a multimeter that’s set to the lowest Ohms of resistance, touch the probes of each terminal on the limit switch to test for continuity. If the limit switch has continuity, the multimeter will be reading 0 Ohms. If the limit switch is faulty, the multimeter will show infinite resistance and should be replaced.

How to fix a malfunctioned Goodman furnace limit switch

To replace a malfunctioned Goodman furnace limit switch, follow these steps:

  1. Turn off power to the furnace.
  2. Remove the outer cover panel of the furnace.
  3. Locate the limit switch on the side of your furnaces housing and disconnect the wires.
  4. Remove the screw to take out the limit switch.
  5. Place the new limit switch where the old one was removed and screw it into place.
  6. Reconnect the wires.
  7. Replace the outer cover.
  8. Open the gas valve and turn on the power. Your furnace should resume normal operation.

A Bad Blower Motor

A Goodman blower motor causes the fan to spin and blow hot air through the ducts and vents into your home. If the blower motor is damaged there will be no air reaching your home through the vents.

A bad blower can be a result of rust accumulation around the motor due to excessive moisture in the furnace room, excessive dust, and debris that causes faster blower motor wear or overheating. Any of these issues can accelerate wear on the blower motor’s windings and bearings.

How to diagnose a bad Goodman furnace blower motor

You can tell that your Goodman furnace blower motor is bad if:

  • There’s poor airflow through the vents into your home or no airflow at all.
  • The furnace makes a loud humming or buzzing noise when turned on.
  • There’s a smell of burning from the air vents.
  • The energy bills are going up.

How to fix a bad blower motor

Call an HVAC pro to replace a bad Goodman furnace blower motor. Doing so requires knowledge about the blower motor’s type of drive, horsepower, rotation direction, speeds and voltage, size of the capacitor, and diameter of the motor, which is why a DIY repair may not be advised.

Blocked Air Ducts

Air ducts carry heated air from the furnace to your home. If any blockage happens in the ductwork, the flow of air is obstructed. 

Blocked air ducts can result from the buildup of fluff and debris or objects accidentally pushed into the ducts. Also, if the ductwork is poorly installed, parts of the insulation can fall off and block the airway.

Besides, air duct blockage can result from closed butterfly valves, the valves that control the flow of air through the specific ducts that sent it to each room.

How to diagnose and fix blocked furnace air ducts

To tell if there’s a block in the ductwork, you’ll notice that hot air will not be blowing into your home through the vents. Place your hand in front of an air vent to detect the presence or absence of hot air from the ducts.

Once you’ve ascertained that there’s no air blowing into your home and there’s an indication the ducts could be blocked, unscrew the vent cover and remove it. Check first that no objects are piled directly behind the vent grill, then check for blocking objects at the pipe-bend that feeds air to the room, and lastly proceed to check inside the ducts. 

Use a flashlight to inspect the ductwork while ensuring the air path is clear and the seams are intact. If any loose duct tape is found or duct seams are separated, reassemble them using stronger quality duct tape. The Gorilla 6003514 Duct Tape is preferred for its heavy-duty thickness. It permanently sticks on any type of surface while still possible to rip by hand. Most especially, it withstands moisture and extreme temperatures.

While you are at it, locate the butterfly valves and check to ensure they are open and letting air through. Open butterfly valves have their handles parallel to the ductwork. If the handles are perpendicular to the ductwork, the valves are closed and you should open them.

If the ductwork has extensive damage, call an experienced HVAC expert to do the repairs.

Goodman Furnace Not Getting Gas

If your Goodman furnace is not getting gas, the gas supply is cut or the gas tank is empty, the gas supply valve is closed, or the Solenoid valve is bad. An accidentally closed gas supply valve is more common and can easily be troubleshot by opening it.

No Gas Supply

The first cause for a Goodman furnace not getting gas is that the gas supply is stopped. If you are on the utility gas supply, it could be a problem in the line that is causing the shortage. If instead, you use a propane or LP gas tank, the tank could be empty. 

How to diagnose and resolve furnace gas supply issues 

If your furnace uses gas from the municipal supply line, it will be hard to tell if the gas supply is cut unless you have other home appliances served by the same line and you can test if they are receiving gas.  If that is not the case, call a professional HVAC or the municipal gas agency for your city to assess your natural gas supply.

If you use a propane or LP gas tank, check the gas pressure gauge to tell if the tank is empty and have it refilled.

Closed Gas Supply Valve

A closed furnace gas supply valve blocks the flow of gas to your furnace. The valve can be closed accidentally or when the furnace was not running.

How to diagnose a closed Goodman furnace gas valve

Locate the gas supply valve on the side or at the back of the furnace. A closed gas valve is at a quarter turn or perpendicular to the gas line.

How to fix a closed Goodman furnace gas valve

To open a closed Goodman furnace gas supply valve, rotate the valve in a counterclockwise direction until the long side of the handle is parallel to the gas line.

Bad Solenoid Valve

A solenoid valve is an electronic component in your furnace that is controlled by the thermostat and is wired to a gas valve to limit, increase, or close gas supply depending on the obtained temperature in your home. For example, if the temperature in your home is low, the solenoid valve will supply more gas and close the valve if the desired heat is obtained. If this valve is bad, it can cause the gas supply to be permanently closed.

How to test and fix a bad solenoid valve

Testing and replacing a bad solenoid valve is a complex process involving several electrical connection wires. Call in an HVAC pro to perform the service.

Goodman Furnace Not Working, No Codes

If your Goodman Furnace is not working and there are no error codes, there’s no 115volt power to the furnace, no 24volt power to the integrated control module, there’s a problem with a blown fuse or circuit breaker, or the integrated control module has an internal fault.

These problems can occur due to one of these causes:

  • A manual disconnection (furnace is switched off).
  • An open door switch.
  • Improperly connected or loose 24volt wires.
  • A blown fuse or tripped circuit breaker.
  • An internal fault with the integrated control module.

How to fix a Goodman furnace not working with no codes

If your Goodman furnace is not working and has no error codes, call an HVAC technician or troubleshoot with one of these options depending on the problem:

  1. Check if the furnace power switch is turned off and turn it on.
  2. Confirm the presence of 115volt and 24volt power to the furnace’s integrated control module.
  3. Check and replace the integrated control module fuse if necessary.
  4. Assess the furnace for possible shorts in 115volts and 24volt circuits and repair accordingly.
  5. Replace a blown fuse or switch back on a tripped circuit breaker.
  6. Replaced a bad integrated control module.

Goodman Furnace Blowing Cold Air

If your Goodman furnace is blowing cold air, the thermostat settings are wrong, power issues are causing the thermostat to malfunction, or the air filter, flame sensor, or gas burners are dirty. Wrong thermostat settings are most common and easily corrected with the right settings.

Incorrect Thermostat Settings

A wrong thermostat setting can mess up the functioning of your Goodman furnace. If the furnace fan is set on the ON mode, it means your furnace’s fan will blow air nonstop even though the furnace is not heating. So, if you have set your thermostat at 72 degrees, the fan will be blowing cold room temperature air. If instead, your Goodman furnace is set on the AUTO mode, and at 72 degrees, it will blow hot air once the temperature drops below the set temperature.

Also, if your thermostat is set on COOL instead of HEAT mode, the furnace will send cold and not hot air.

How to fix wrong thermostat settings

Check your thermostat fan settings and turn it to the AUTO mode if it is in the ON mode and on the HEAT and not the COOL mode.

Thermostat Power Issues

If your Goodman furnace’s thermostat has power issues, it will now work correctly. Power issues with your thermostat can be caused by several factors including these two:

  1. Low thermostat batteries 

If your thermostat works with batteries and the batteries are low, the thermostat may start sending erroneous temperature readings to your furnace, causing it to blow cold air when it should be blowing hot air.

How to fix low thermostat batteries

If you have a digital furnace thermostat, it will beep or flash to show a low battery depending on the model. Alternatively, you can open the outer panel of the thermostat and test the batteries for continuity. 

Low charge or dead batteries (batteries with less than 1.35 volts for the AA/AAA type and 2.7/2.8 volts for 3V lithium batteries) will need to be replaced. Consult your furnace’s user manual or follow these steps to replace the batteries: 

  1. Remove the thermostat’s outer casing.
  2. Locate the thermostat batteries. Thermostats use 3V lithium batteries, AAA, or AA alkaline batteries. The 3V lithium batteries are stronger and recommended.
  3. Remove the old batteries and replace them with the new ones, ensuring they fit in the same position.
  4. Put back the thermostat’s outer casing.
  5. Reprogram the thermostat to the desired settings and get the furnace running to heat your home. 

If this process seems complex, call in an HVAC pro to help you out.

  1. Loose thermostat wires/wrong wire connection

If your thermostat is mishandled and gets disconnected from the wall, the wires can get loose and cause the thermostat not to communicate properly with the furnace, which could mean not sending the signal to blow hot air. 

Also, if your thermostat is just installed, wrong wire connections can cause the thermostat to send the wrong data to the furnace. 

How to fix loose thermostat wires or wrong wire connection

If you’ve just installed your furnace and the thermostat does not work or is working wrongly, consult the Installation Manual of your furnace to confirm that the wires that connect the thermostat to the furnace are correctly installed. Alternatively, call the installer to check if the connections are correct.

If the thermostat wires are loose, tighten them and check if your furnace and thermostat resume working normally.

Clogged Air Filter

A clogged air filter is one of the common culprits when your furnace is not blowing hot air. The filter prevents dust and debris from getting into your furnace together with the air that’s heated and sent to your home. If the filter is clogged, little air will not get into the furnace and your heating system will have limited air to heat and send to your home. Besides, the furnace can overheat from running for longer cycles and stop working.

How to fix a clogged furnace air filter

It is recommended that your change (clean) your Goodman furnace filter every 3 months. If you are not good at remembering when to change your furnace filter, consider a filter subscription program such as Subscribe & Save from Amazon.

Read details about how to fix a clogged air filter in the earlier section on “Goodman Furnace not Heating/Not Blowing Hot Air.”

Note too that choosing the right air filter for your Goodman furnace can help you ensure the furnace heats the air as it should. For example, while a standard furnace filter will keep the air ducts clean, it will not clean the air as happens with a media filter which is 7 times more efficient. A pleated media filter is even better as it also eliminates airborne viruses and insecticides. 

A Dirty Flame Sensor

Most furnaces today have a flame sensor and not a pilot flame. The flame sensor keeps the flames at the burner on once they are lit. If the flame sensor is covered with dirt, it will not sense the flame and the furnace may turn off when it should stay on, explaining why it will be blowing cold air.

How to clean a dirty flame sensor

Read details on how to clean a dirty furnace flame sensor in the earlier section on “Goodman Furnace Won’t Stay Lit/Keeps Shutting Off.”

Dirty Gas Burners

Dirty gas burners reduce the amount of oxygen that is needed to keep them lit and burning. A poor flame can reduce the amount of heat needed to heat the air and send it hot to your home.

How to fix dirty gas burners

The best way to keep your Goodman furnace gas burners clean and functional is to ensure the annual maintenance for your furnace is done by a professional. However, if you should find yourself with dirty furnace burners, follow these steps to do a troubleshooting cleaning or call a professional HVAC technician to do the same:

  1. Turn off the power supply to the furnace.
  2. Remove the wires that may be on the way of the furnace burners. If you are not sure which wire goes where, mark them as you disconnect them.
  3. Remove the screws holding the burners to the unit, then unhook the burners to remove them.
  4. Use a wire brush to rub the surface of the burners to remove any dirt or rust. Ensure that the gas channels and burner holes are clear of any dirt.
  5. Use a vacuum to eliminate any remaining dirt from the holes and burner tubes.
  6. Replace the burners, making sure they fit back into the hooks.
  7. Switch the furnace back on to start heating your home.

This video can serve as a visual demonstration of these steps.

Goodman Furnace Leaking Water

If your Goodman furnace is leaking water, the condensate pipe is cracked, the drain line is clogged, the condensate pump is defective, the heat exchanger is cracked or the furnace humidifier is leaking. A clogged drain line is most common and should be unclogged to allow a clear flow of condensate.

Cracked Condensate Pipe

The Condensation from your high-efficiency Goodman furnace drains into the condensate pan and through a condensate pipe into the main drainage line. If the condensate pipe is cracked, the condensate will leak, which is why you may find a pool of water around your furnace. 

How to diagnose a cracked condensate pipe

Check the condensate pipe connected to your furnace to notice any cracks or a loose joint, then proceed to repair or replace the pipe as the case requires.

How to fix a cracked condensate pipe

If your Goodman furnace condensate pipe is cracked, you may need to cut out the bad part and replace it with coupling joiners or replace the entire pipe altogether. If the problem is a loose joint, push back the pipe into place and use pipe cement to firm it in place.

Clogged Furnace Drain Line

Once the condensate produced in the heating process drains into the condensate pan, it is delivered into the main drain line through the furnace condensate pipe. If the drain line is clogged, the condensate water will flow back and leak onto the furnace or around it.

How to diagnose a clogged furnace drain line

While a leak will be the first sign you see if the furnace drain line is clogged, plenty of water standing in the drain pan is another sign of stalled furnace drainage.

You can also check the drain line outlet outside your home to see if any water is exiting from there, if not, the drain line is most likely blocked. 

How to fix a clogged furnace drain line

If assessing your furnace drain line suggests that it is clogged, follow these steps to unclog it:

  1. Turn off the furnace.
  2. Dry out the water standing in the drain pan by soaking it with a sponge or rag and squeezing it out into a bucket.
  3. Suck out the water standing in the drainpipe using a shop vacuum.
  4. Insert a piece of long thin wire to pull out any objects blocking the drain line. You can also use a plumber’s snake if you have one. The Vastar Drain Snake is a good easy to use choice. The 19. 6″ flexible barbed wand will remove any soft objects blocking your furnace drain line and is cheaper and more environmentally friendly than chemical drain cleaners. Besides, it comes in a 3 pack that you can use for the longest.
  5. Throw a mixture of warm water, vinegar, and a little kitchen detergent into the drainpipe to clear any remaining dirt in the drain line. 
  6. Turn on the furnace to test if the clog and resulting leak are resolved.

If you want a long-term solution for furnace drain line clogging, you can also consider using condensate pan tablets. These are left in the condensate tray and will prevent the drain line from clogging. Product options like the Outland Air Conditioner Pan Cleaner Tablets will not only keep your drain line free of clogs but it is also nontoxic and prevent bad odor.

Defective Condensate Pump

Your Goodman high-efficiency (condensing) furnace drains down. This condensate will need to be pumped up and out of your furnace is installed in the basement and a floor drain is not practical.

If the condensate pump is stuck or broken, the condensate will build up and run out of the condensate pump reservoir. 

How to diagnose and fix a defective furnace condensate pump 

  1. Clean up the water around the pump.
  2. Open the pump and use your hand to move the float switch to see if it moves freely, if it does, then the pump has other issues.
  3. Next, fill the condensate pump reservoir with water if it’s empty and see if the pump starts running. You’ll need to put enough water to raise the float switch and activate the pump.
  4. Notice any leaks at the bottom of the reservoir as this could mean it’s cracked.
  5. If the pump runs but the water is not reducing, then the check valve could be clogged and needs to be cleaned
  6. To unclog the check valve, turn the furnace off and disconnect the pump.
  7. Remove the condensate discharge tube and drain the water in it into a bucket.
  8. Unscrew the check valve and use compressed air to clear it of any blockage.
  9. Reconnect the check valve and the pump and turn on the furnace to test if the pump resumes normal operation.
  10. If this does not resolve the issue, the pump is internally blocked and should be replaced.
  11. To replace the pump, loosen the mounting screws (or unhook the mounting bracket) and remove the inlet pipes, then swivel the pump away.
  12. Place the new pump in place of the old and reconnect the pipes. Your new condensate pump should start working and you can run the furnace again.

A Cracked Heat Exchanger

The heat exchanger in your Goodman furnace transfers heat from the furnace combustion chamber to the ducts that send it to your home through the vents. If the heat exchanger is cracked, the moisture from the heating process might leak out of the furnace through it. Besides, a cracked heat exchanger also sends toxic gases to your home.

How to tell if your Goodman furnace heat exchanger is cracked

Apart from a leak, a cracked heat exchanger comes with several other signs:

  • A yellow furnace flame
  • Furnace produces plenty of soot.
  • A formaldehyde-like smell from the furnace.
  • Corrosion and cracking on other parts of the furnace.
  • Rattling noises.

How to fix a cracked Goodman furnace heat exchanger

Trying to troubleshoot a cracked furnace heat exchanger is an absolute no, no! Instead, call a professional HVAC technician who will disassemble a number of furnace parts to have access to the heat exchanger and assess it for cracks.

A cracked heat exchanger has to go. In fact, most HVAC pros will advise you to replace the furnace because cracked heat exchangers are usually characteristic of furnaces that have done their time.

A Leaking Humidifier

If your furnace works with a humidifier, the leak could be from the humidifier and not the furnace. Humidifier leaks can be caused by:

  • Blockage in the waterline.
  • Valve reversal.
  • An open valve.
  • High water pressure.

How to diagnose a furnace leak from the humidifier

The easiest way to find out if the leak on your furnace is from the humidifier is to shut off the water supply to the humidifier and see if the leak stops.

You can also check your furnace to notice a buildup in humidity and search for leaks at the water tap line, water feed tube, or humidifier casing.

How to fix a furnace leak from the humidifier

Call in a plumber if the water line supplying your furnace humidifier has leaks so he can do the necessary repairs.

Goodman Furnace E5 Error Code

Goodman furnace error E5 is an open fuse error that comes with no furnace operation and a “Battery Power” display on the thermostat. It is caused by a short circuit in low voltage wiring.

How to fix Goodman furnace error E5

Call an HVAC expert to locate the low voltage wiring that has shorted and correct it. The furnace should be powered off when this is done.

Goodman Furnace Solid Red Light

If your Goodman furnace has a solid red light on, the furnace control board has an internal fault and will not be operating.

How to fix Goodman furnace solid red light malfunction

To fix a Goodman furnace solid red light malfunction, replace the control board as this is a sign it is faulty. Ensure the furnace is not powered before proceeding.

Goodman Furnace Yellow Light Flashing

If your Goodman furnace yellow light is flashing, it could be for normal operation if there are 1 or two flashes or for malfunction if there are 3, 4, or rapid flashes. 

Goodman Furnace Yellow Light 1 flash repeating

If your Goodman furnace yellow light has 1 flash repeating, this is a normal operation with a low-stage call for heat by the connection terminals of the thermostat.

How to fix Goodman yellow light 1 flash repeating

Goodman yellow light 1 flash repeating is a normal operation indicator and no action is required.

Goodman Furnace Yellow Light 2 flashes repeating

If your Goodman furnace yellow light has 2 flashes repeating, this is a normal operation with a high or single-stage call for heat by the connection terminal of the thermostat.

How to fix Goodman yellow light 2 flashes repeating

Goodman yellow light 2 flashes repeating is a normal operation indicator and no action is required.

Goodman Furnace Yellow Light 3 flashes repeating

If your Goodman furnace yellow light has 3 flashes repeating, this is a malfunction and the furnace will not operate. It is caused by a heat call from one of the connection terminals of the thermostat and not the other in a two-stage furnace model.

How to fix Goodman yellow light 3 flashes repeating

To fix Goodman yellow light 3 flashes repeating malfunction, call an HVAC pro to check the thermostat or thermostat wiring for faults or improper thermostat wire connections.

Goodman Furnace Yellow Light 4 flashes repeating

If your Goodman furnace yellow light has 4 flashes repeating, this is a malfunction where, while in the cooling mode, there’s a call in the first stage in a two-stage cooling (Ylo) and the second stage in a two-stage cooling (Y) but not in the fan input (G).

How to fix Goodman yellow light 4 flashes repeating

To fix Goodman yellow light 4 flashes repeating malfunction, call an HVAC expert to check the thermostat or thermostat wiring for faults or improper thermostat wire connections.

Goodman Furnace Yellow Light Rapid flashes

If your Goodman furnace yellow light has rapid flashes, this is a malfunction and the furnace will not be operating. It is caused by a low flame sensor current.

How to fix Goodman yellow light rapid flashes

To fix Goodman yellow light rapid flashes, call an HVAC expert to check the furnace for a dirty flame sensor or faulty flame sensor wire connections, improper gas pressure, or poor flame, and proceed to do the necessary cleaning and repairs.

Goodman Furnace Gas Valve Not Opening

If your Goodman furnace gas valve is not opening, the gas valve could be stuck or the solenoid valve faulty. These are not common malfunctions but, when they occur, they should be addressed by an expert HVAC technician or municipal gas agent.

A Stuck Gas Valve 

A furnace gas valve that will not open may be stuck in the closed position, which means there will not be any gas flowing to your furnace. This could be caused by internal issues in the gas valve, cracked or frayed gas valve wires, or a malfunctioned coil at the gas valve.

How to diagnose a stuck furnace gas valve

If your Goodman furnace is not receiving gas, chances are the gas valve is stuck. If the gas valve is open but not doing its work, check for frayed or cracked gas valve wires. Also, test the gas valve coils for resistance by placing the multimeter leads on each terminal. If the multimeter reading shows OL, your gas valve coil is bad. 

How to fix a stuck furnace gas valve

We absolutely discourage you from trying to troubleshoot furnace issues that have to do with gas supply. Even though you will read advice that tells you to hit or bang your furnace gas valve to unstuck it or use a wrench to loosen it, desist from doing any of these.

If you do this and your furnace has more problems or a fire results from furnace gas issues (perish the thought!), your insurance company can claim innocence if they discover you tampered with the gas valve.

Always call an experienced HVAC or municipal gas supply agent to assess and resolve furnace gas issues. In reality, gas valves are usually not repaired in the field, and it’s best to take advice from an expert.

A Bad Solenoid Valve (Printed Circuit Board)

During a furnace igniting process, 24 volts are sent to the gas valve after the ignitor turns on so it can supply the gas and get all the burners on.

If this is not happening and the gas valve is not opening, the solenoid or printed circuit board that sends the message to the gas valve to open and control the flow of gas to the burners could be faulty. 

How to diagnose and fix a bad solenoid valve

Call an HVAC expert to assess and replace a bad solenoid board. Trying a DIY approach here is not advised.

Goodman Furnace Making Loud Noise

If your Goodman furnace is making a loud noise, the heat exchanger is cracked, the ductwork is old or poorly installed, the blower is defective or the draft inducer motor is bad. A defective blower or defective inducer motor are more common since they are in continuous motion. Have them replaced.

Cracked Heat Exchanger

A loud furnace noise soon after it’s turned on could be caused by a crack in the heat exchanger. Because it is made of metal, a crack in the heat exchanger will expand when heated, causing a loud bang noise.

How to diagnose a crack in the heat exchanger

Apart from the loud noise from a cracked heat exchanger, there are other signs that could indicate your Goodman furnace heat exchanger has a crack:

  • A yellow flame
  • Plenty of soot produced by the furnace.
  • A formaldehyde-like smell.
  • Corrosion and cracking on other parts of the furnace.

How to fix a cracked Goodman furnace heat exchanger

This is not one of the issues you can troubleshoot. Call an expert HVAC technician immediately if your Goodman furnace is making loud noises soon after it’s turned on and if you notice the above signs of a cracked furnace heat exchanger.

Because old age is a common reason for a cracked heat exchanger, the HVAC pro will most likely advise you to replace your furnace.

Old or Poorly Installed Ductwork

If it seems to you that the loud noises coming from the furnace are from the ductwork region, then it might be that the ductwork is getting dated or was poorly installed. As such, once the furnace is turned on, the heat causes the loose or old metal to expand and move, consequently making loud noises.

How to assess aging or poorly installed ductwork

The best way to tell if your ductwork is dated is by recalling the age of your furnace and of any repairs made to the ductwork. If it appears that the years have accumulated and the ductwork may be giving in to the extreme heat and time, then it is time to repair it. 

To check if there are signs of poorly installed ducts, open the vent grill in your home and use a flashlight to check for signs of loose duct pieces.

How to fix aging or poorly installed ductwork

Call in an expert HVAC technician to advise you on the status of your furnace ductwork and make the necessary repairs.

A Defective Furnace Blower

There are two issues that can cause your Goodman furnace blower to make loud noises: 

  • a loose blower wheelset screw and 
  • worn-out blower motor bearings.

The furnace blower wheel is attached with a set screw to the blower motor shaft. If this screw is loose, the blower wheel will run wobbly on the motor shaft, causing it (the wheel) to make loud noises as it turns.

Worn-out blower motor bearings come with time as the blower motor is in consistent motion. They will compromise the way the fan blades spin in the blower housing, which is why the blower will be making loud noises.

How to diagnose a noisy defective furnace blower

When you open the outer cover of your Goodman furnace and locate the blower motor, it is easy to tell that the loud noise is coming from the blower if you get the furnace running. You can look at the turning of the blower to see if it’s wobbly and listen to tell if the loud noise is kind of grinding, suggesting worn-out blower motor bearings. 

How to fix a noisy defective furnace blower

If the blower wheel is the cause of the noise, switch off the furnace and turn the set screw to see if it is loose. If it is, tighten it so the blower wheel turns normally. 

Beyond this, we suggest you call in an expert HVAC technician to resolve your furnace blower issues. Replacing a damaged blower wheel and worn out bearings requires quite some screwing and dismantling, which is why you should let an expert handle it and avoid causing more damage. 

Bad Draft Inducer Motor

Just like the blower, a bad draft inducer motor, one whose bearings are worn-out or the inducer blower wheel damaged, can cause loud noises in your furnace.

How to diagnose and fix a bad and noisy furnace draft inducer motor

Repeated loud noises from the draft inducer motor are already enough sign that it should be replaced. 

You can confirm that your draft inducer motor is damaged by opening the furnace outer cover and checking to see if the center hub of the blower wheel is separated or the fins are broken.

Call in an HVAC technician to replace a bad draft inducer motor.

Goodman Furnace Just Clicks/Keeps Clicking

If your Goodman Furnace just clicks or keeps clicking, it has an ignition problem that could be caused by a lack of gas supply, dirty gas burners, or a faulty flame sensor. A closed gas supply valve is the most probable cause and can be resolved by opening the valve.

No Gas Supply

If your furnace is trying to turn on and there’s no gas supply or the supply is insufficient, it will make a clicking sound. 

Lack of gas supply to your furnace can be caused by a closed or faulty gas valve, lack of gas from the utility line, or an empty propane/LP gas tank.

How to diagnose furnace clicking due to no gas supply

Check first that your furnace gas supply valve at the back or the side of the furnace is open. If it is open, proceed to check if your Goodman furnace is actually receiving gas from the supply line or tank by turning on other home equipment running on gas such as the cooker to test if they are receiving gas. Remember that it’s dangerous to use methods that involve fire to try and see if gas is running to your furnace.

How to fix furnace clicking due to no gas supply

First, open the gas supply valve if it turns out that it is closed. A closed gas supply valve is at a quarter turn or perpendicular to the gas line. Instead, an open gas valve stands parallel to the gas line. Turn the valve in an anticlockwise direction to open it.

If the issue is with the gas supply, call an HVAC pro or the municipal gas supply agency to check your gas line. Alternatively, ensure your propane/LP gas tank has fuel by checking the pressure gauge and refilling it if empty. 

Dirty Gas Burners

Dirty gas burners can block or limit the flow of gas, stopping the flame from starting and staying on. If this is the case, your furnace may keep clicking in an effort to draw gas and light the burners. 

How to diagnose dirty furnace gas burners

To check if your Goodman gas burners are dirty and blocking or limiting gas flow, causing the furnace to click, follow these steps:

  1. Turn off the furnace.
  2. Disconnect any wires that could block your way to the burners. Ensure you can reconnect them in their right ports by marking the wires or taking pictures.
  3. Unscrew the burners and unhook them to remove. 
  4. Assess to see if the burners’ holes and channels are blocked by dirt or rust and proceed to clean them.

How to clean dirty furnace gas burners

To clean dirty furnace gas burners:

  1. Use a wire brush to rub and remove any dirt in the burner holes and gas channels. Once all the dirt is loosed, use a vacuum to rid the burners of any remaining dirt.
  2. Place back the burners, ensuring they fit back into the hooks, then screw them in their place.
  3. Reattach the connection wires to their ports.
  4. Turn on the furnace and listen to make out if the clicking noise is resolved. 

A Faulty Flame Sensor

A flame sensor detects the presence of a flame and keeps the furnace running. If it is faulty, it will not detect the flame and can keep your furnace clicking in a bid to detect a flame and start running. 

How to diagnose a faulty furnace flame sensor

A faulty flame sensor will cause your furnace to turn off as soon as it lights. But you will also notice plenty of soot or corrosion covering the flame sensor or find that the porcelain insulation on the sensor is cracked. Besides, the flame sensor may keep clicking to try and sense the presence of a flame. To check for these signs:

  1. Turn off the furnace.
  2. Close the gas supply valve.
  3. Open the outer panel of the furnace and locate the flame sensor.
  4. Locate the flame sensor and assess it for soot and corroding or cracked/damaged sensor insulation.

If the sensor is just dirty or corroded, you can simply clean it and it should start working, which means the clicking should stop. If the flame sensor has cracked/damaged insulation, you need to replace it.

How to replace a faulty furnace flame sensor

To replace a bad furnace flame sensor:

  1. Turn off the furnace.
  2. Close the gas supply valve.
  3. Open the outer panel of the furnace and locate the flame sensor.
  4. Unscrew the bad flame sensor and pull it out.
  5. Take the new flame sensor and screw it in place of the old one.
  6. Turn on the furnace to see if the flame sensor has stopped clicking. 

Goodman Furnace Making Buzzing or Humming Noise

If your Goodman furnace is making a buzzing or humming noise, there’s an electrical issue with the transformer, capacitor, or blower motor. The transformer box could also be loose. A bad capacitor is the most common cause of a buzzing or humming sound from a furnace and should be replaced.

Loose Transformer Box

The standard voltage output in your home is 120volts. But some furnace parts need less than that to run. To ensure that the furnace parts receive the required voltage, your heating system has a transformer that regulates your home’s electrical voltage so that it is sent to the furnace in the required amount for the ignition, timers, circuitry, and temperature controls.

The transformer box is found inside the furnace housing, so, if it is loose, it can create a buzzing or humming noise.

How to diagnose a loose furnace transformer box

Open your furnace outer panel and locate the transformer box, usually in the lower compartment. Observe the transformer box while the furnace is running to see if it is shaking more than it should and listen to notice a buzzing or humming noise.

How to fix a loose furnace transformer box

Switch off the furnace and tighten any loose screws holding the transformer to the furnace housing with a screwdriver. Then try running the furnace to see if the buzzing or humming sound has stopped. If the transformer still buzzes, then it could be faulty and needs replacing. In that case, call in a professional HVAC technician to confirm diagnosis and repair/replace the transformer as required.

Malfunctioning Furnace Capacitor

The capacitor in your Goodman furnace sends an electrical signal to the blower motor to start. If the capacitor is malfunctioning and unable to send the electrical signal, it can make a buzzing or humming sound.

How to diagnose a malfunctioning furnace capacitor

To check if the furnace capacitor is malfunctioning and making a buzzing or humming noise, follow these steps:

  1. Turn off the furnace.
  2. Remove the outer panel and locate the furnace capacitor close to the blower motor.
  3. Turn on the furnace and notice any buzzing or humming sound from the capacitor. If this is the case, the blower motor will most likely not be running or will run in an inconsistent rhythm due to an erratic power supply. 

You can also confirm that the capacitor is malfunctioning by using a multimeter that can read both voltage and Micro Farads. If your capacitor records a lower number of Micro Farads than what it is rated for, then it is bad and needs to be replaced. Ensure you order one with similar ratings.

How to fix a malfunctioning furnace capacitor

We recommend you call a trained HVAC technician for any electrical issues with your furnace, including a malfunctioning capacitor. If you are confident about your repair skills, however, here’s what you should do to troubleshoot a malfunctioning furnace capacitor:

  1. Switch off the furnace.
  2. Open the furnace by removing the outer panel and locate the furnace capacitor close to the blower motor.
  3. Disconnect the capacitor wiring and mark the wiring positions to ensure you replace them back accordingly. You can take pictures for reference.
  4. Remove any screws or bolts holding the capacitor in its place and remove the capacitor.
  5. Place the new capacitor where the old one was and screw/bolt it in place.
  6. Reconnect the capacitor wiring.
  7. Turn the furnace back on and listen to notice if the buzzing or humming sound is resolved and the capacitor is working normally to run the motor.

A Failing Blower Motor

The blower motor rotates the fan so hot air can be sent from the furnace to your home. If the motor is broken or, for some reason, cannot effect the electrical signal from the capacitor to start running, then it can produce a buzzing or humming noise.

How to diagnose a failing furnace blower motor

Open the outer cover of your furnace and locate the motor. Try running the furnace when open to tell if the buzzing or humming noise is coming from the blower motor. A failing motor will likely be attempting to start in vain, which is why it will be making the buzzing or humming noise.

How to fix a failing furnace blower motor

A blower motor with electrical issues is best addressed by an expert. Call in an HVAC pro to test the blower motor for faults and repair/replace it as needed.

Goodman Furnace Keeps Blowing Fuse

If your furnace keeps blowing fuse, it has an electrical problem resulting from a wrong fuse size or electrical strain, a malfunctioning furnace transformer, stray thermostat wires, or loose connection wires.

Wrong Fuse Size/Electrical Strain

Most furnaces come with a 3-5 amp fuse. If your Goodman Furnace should have a 3A fuse but has one with a lower amperage than what is recommended for the furnace, then the furnace will cause electrical strain to the fuse and cause it to blow.

How to tell and fix a wrong size fuse

Simply check the amperage on your furnace fuse and compare it with what is recommended on the User/Service Manual of your Goodman furnace model. Locate the fuse on the upper left side of the circuit control board and replace it with the recommended size of the fuse.  

Malfunctioning Furnace Transformer

A furnace transformer regulates the power supply so that the correct amount is sent to furnace parts. If the transformer is malfunctioning and sending more voltage to the fuse than needed, then it will cause it to blow.

How to diagnose and fix a malfunctioning furnace transformer

Desist from troubleshooting complex power issues with your furnace. Power issues with a transformer is one of them. So, if your furnace fuse keeps blowing and you suspect the transformer, call in an expert HVAC technician to assess it and make the necessary repairs or replacement.

Stray Thermostat Wires

If you have a thermostat wire that’s moved from its usual position and is touching the metal frame of the furnace, this can cause it to send more voltage to the wire than required, leading to a blown fuse at the control board.

How to resolve stray thermostat wires

Homeowners may not know what position wires in their furnace should take. As such, to prevent consistent fuse blowing, ensure the annual furnace maintenance is done. Call in an HVAC pro if you think thermostat wires are causing your furnace fuse to keep blowing.

Loose Connection Wires

Because it is consistently in motion, a vibrating furnace can cause connection wires to loosen. A loose electrical wire is a fertile ground for an electrical short, which could target the fuse and blow it.

How to fix loose furnace connection wires

It’s difficult to guess when a connection wire in your furnace is loose. Prevent this from happening by having an expert HVAC technician make the annual furnace maintenance on your furnace. If you suspect issues with your furnace wires are causing the fuse to blow, call in an HVAC pro immediately to assess the furnace’s electrical connections.

Goodman Furnace Keeps Locking Out

If a Goodman furnace keeps locking out, the flame sensor is dirty or defective, the ignitor is faulty, or the limit switch is tripped or closed. A dirty flame sensor is the most common cause of a furnace that keeps locking out and can be resolved with cleaning.

Dirty/Defective Flame Sensor

When your Goodman furnace is turned on, the flame sensor tries to detect the presence of fire.  If the flame sensor is covered with soot or corrosion or the porcelain insulation is damaged, it will not detect the flame and the furnace will shut off. 

Trying to restart a furnace with a defective flame sensor several times will cause your furnace to go into a lockout.

How to diagnose a Goodman furnace lockout due to a defective flame sensor

A furnace lockout is a situation where the furnace sensor detects an unsafe condition for furnace operation and the furnace controller shuts off power and fuel to prevent dangerous operation. 

When a Goodman furnace locks out, the diagnostic light will show one short flash followed by a longer pause.

How to fix a defective flame sensor and resolve furnace lockout

If your Goodman furnace locks out due to a defective flame sensor, you should clean or replace your furnace flame sensor as the case requires. Details on how to clean a dirty flame sensor and how to replace a defective flame sensor can be found in the sections on “Goodman Furnace Won’t Turn On” and “Goodman Furnace Just Clicks” respectively.

Note, however, that you’ll still need to reset your furnace if it locks out, even after you have cleaned and replaced a dirty/defective furnace sensor. To reset your Goodman furnace after a lockout, consider one of these options:

  1. Turn off the thermostat for a period of not less than 5 seconds and not more than 20 seconds.
  2. Turn off the furnace for a minimum of 5 seconds.
  3. Leave the furnace to automatically reset after 1 hour of lockout.

A Faulty Ignitor

If your Goodman furnace ignitor does not activate seconds after the furnace is turned on, the flame sensor will not detect fire and the furnace controller will stop the furnace ignition process. If the attempt to ignite happens 3 times in a row, the furnace will go into lockout mode.

How to diagnose a faulty furnace ignitor

To tell if your Goodman furnace ignitor is faulty, test it for continuity following these steps

  1. Turn of the furnace.
  2. Remove the furnace cover.
  3. Locate the ignitor and disconnect the wires.
  4. Unscrew the bolt that holds the ignitor to remove it. Be careful not to touch the element.
  5. Set your multimeter to the lowest resistance Ohms (OL).
  6. Touch the probes with each terminal. An ignitor with continuity will read between 50-200 Ohms. If there’s no continuity, the reading will not change from zero or will only show a slight change. In this case, the ignitor is faulty and should be replaced.

How to replace a faulty furnace ignitor and resolve lockout 

To replace a faulty Goodman furnace ignitor, follow these steps:

  1. Turn of the furnace.
  2. Remove the furnace cover.
  3. Locate the ignitor and disconnect the wires.
  4. Unscrew the bolt that holds the ignitor to remove it.
  5. Slide the new igniter where the old one was and tighten the bolt.
  6. Reconnect the wires.
  7. Turn on the furnace and reset the furnace using one of these options:
  • Turn off the thermostat for a period of not less than 5 seconds and not more than 20 seconds.
  • Turn off the furnace for a minimum of 5 seconds.

A Tripped/Closed Limit Switch

The limit switch in your Goodman furnace regulates the heat exchanger temperatures and fuel pressure. If the temperatures go to the extremes (too low or too high), the limit switch closes and directs the furnace to go into lockout mode. Poor airflow from a dirty filter can also cause the limit switch to trip, causing a furnace lockout.

How to diagnose a faulty limit switch and a resulting lockout

A Goodman furnace with a faulty limit switch will display four flashes on the LED. This should warn you that a furnace lockout is imminent.  Also, furnace lockout will be communicated by a single short flash followed by a longer pause. 

How to fix a faulty limit switch and resolve a resulting furnace lockout

Your need to diagnose the limit switch for faults and replace it if you conclude that it’s faulty. Find details on how to diagnose and replace a faulty limit switch in the section on “Goodman Furnace Won’t Shut Off.”

Remember that replacing the limit switch will not get the furnace running if it is in lockout mode. You’ll still have to reset the furnace manually using one of these methods:

  • Turn off the thermostat for a period of not less than 5 seconds and not more than 20 seconds.
  • Turn off the furnace for a minimum of 5 seconds.

Goodman Furnace Keeps Tripping Rollout Switch

If your Goodman furnace rollout switch keeps tripping, the flue pipe or heat exchanger is plugged or cracked, or the air requirements are not as required. Blockage in the vent pipe is more common and should be resolved by unclogging the vent.

Plugged Flue Pipe or Heat Exchanger

When your furnace burners turn on, the flame takes a corn shape and the flame is sucked straight into the heat exchanger to supply the required heat to your home. At the same time, the flue or exhaust pipe takes in the combustion gases and sends them outside your home through a chimney.

If either the flue pipe or the heat exchange is blocked or they are cracked and are sending back pressure or air into the heating box, the flames will be pushed back and start sending heat where it shouldn’t go. When that happens, the rollout switch detects the unusual high temperatures and trips, closing the gas supply.

How to diagnose restricted flue piping or heat exchanger

Apart from a tripped rollout switch, if your Goodman furnace flue pipe or heat exchanger is clogged, the combustion gases from the exhaust will start going back to your home and the undelivered heat from the heat exchanger will overheat the furnace. 

Installing carbon monoxide sensors can help detect when carbon monoxide levels go up in the home. Also, if you smell burning or feel extreme heat around the furnace, the heat exchanger could be blocked.

You can also find a way of looking inside the exhaust pipe and heat exchanger to see if bird nests, debris, ice, or dead animals are blocking the way of air. 

How to fix restricted flue piping or heat exchanger

You’ll need to unclog a blocked flue pipe and or heat exchanger. In both cases, this could be a tedious and delicate job as both outlets can send back dirt onto your furnace. Besides, you’ll have to remove the hoses of the heat exchanger to clean it. Call in an expert HVAC for a thorough maintenance cleaning.

Most importantly, bear in mind that a tripped rollout switch needs to be manually reset by pushing it down once. But, if the rollout switch keeps tripping, call an HVAC pro immediately as this is bad news, and it comes with risks of fire and carbon poisoning.

Improper Air Requirements

The combustion process in your furnace requires oxygen. So, if your furnace is not getting the needed air for combustion, it will be inefficient and may try to suck back air from the exhaust vent, which means bringing back dangerous gases.

Improper air requirements can be caused by insufficient air intake vents or a dirty air filter.

How to diagnose improper air requirements in your furnace

If your heating system is sending little hot air or is sending cold air to your home, this could be a sign that little air is coming into the furnace. Furnace overheating is also a common outcome, which is what causes the rollout switch to trip.

How to fix improper air requirements and resolve rollout switch tripping

Enhance air intake to your furnace by regularly cleaning the air filter and call in an HVAC technician to install the correct size and amount of air intake vents if you suspect that what is there is insufficient.

Push down the rollout switch to reset it and get your furnace running again. If the rollout switch keeps tripping, call an HVAC pro immediately to assess and resolve the cause.

Goodman Furnace Leaking Water When AC is On

If your Goodman furnace is leaking water when the AC is on, the condensate line is blocked and sending water back to the furnace (most common cause), the AC evaporator coils are frozen and causing an overflow from extra moisture, or the condensate pump is blocked. 

Blocked Condensate Line

Your furnace and AC condensate pipes send the condensate down the same condensate drainage line. If this is blocked during the cooling season when the AC is on, chances are the water from the drain can flow back through the furnace drainpipe onto the furnace and the space underneath it.

Read the earlier section on “Goodman Furnace Leaking Water” to learn how to diagnose and fix a blocked condensate line.

Frozen AC Evaporator Coil

An evaporator coil is that part of the AC’s indoor unit that absorbs the heat from the air so the air can be cooled for your home. To do this, the evaporator coil needs consistent airflow, otherwise, it freezes up. Poor airflow to your AC’s evaporator coil can be caused by a dirty filter, a defective fan blower, a dirty evaporator coil, undersized ducts, and refrigerant issues.

A frozen AC evaporator coil will produce extra moisture when it starts thawing. This could render the drain line inefficient in draining all the extra water and cause the drain pan to overflow. This water may end up under your furnace, giving the impression that your heating unit is leaking.

How to diagnose a frozen AC evaporator coil

To find out if your AC evaporator coil is frozen, follow these steps:

  1. Turn off the AC at the circuit breaker.
  2. Remove the outer cover of the AC by pulling it towards you. This will reveal the filter. 
  3. Remove the air filter. The evaporator coil is located behind the filter.
  4. Assess the evaporator coil for ice buildup.

How to fix a frozen evaporator coil that’s causing a furnace leak

The natural and slower way to fix a frozen evaporator coil is to leave the cooling unit turned off for the time required to thaw the ice. Alternatively, you can set your AC on HIGH fan speed for around 15 minutes to speed up the thawing process. 

A Blocked Condensate Pump

Just like with a furnace, if the condensate from your AC’s cooling process has to be pumped up from a basement, you’ll need a condensate pump for the job. If the condensate pump is defective or blocked, the condensate from the AC will fill up the pump’s reservoir and eventually overflow, causing a pool of water around your AC and furnace if installed in the same space.

How to diagnose and troubleshoot/replace a blocked condensate pump

Read how to diagnose, troubleshoot, or replace a defective/blocked condensate pump from the earlier section on “Goodman Furnace Leaking Water.”

Goodman Furnace Blower Not Working

If your Goodman furnace blower is not working, there’s no power supply, the blower motor is burned out, or the capacitor is bad. A bad furnace capacitor is the most common cause of a bower not working and should be replaced.

No Power Supply

The one obvious reason your furnace blower may not work is that it’s not receiving power. This could be because there’s a blackout, the circuit breaker is tripped, or the control board is faulty and not sending power to the blower.

How to diagnose furnace blower motor power supply issues

You’ll need to perform one or more of these options to make out why your furnace blower is not receiving power:

  1. Try switching on a bulb or other electrical appliances to check if your home is receiving power.
  2. If it’s confirmed that there’s power, check the circuit breaker for signs that the switch supplying power to the blower has tripped.
  3. If the first two are not the cause, have an HVAC pro test your furnace power control board for faults.

How to fix furnace blower motor power supply issues

Depending on the issue that is causing your furnace blower not to receive power, perform one of the following:

  1. Follow up with your area power supply company to have power restored.
  2. Pull up a tripped circuit breaker switch to restore the power supply to your furnace blower. If the switch is hard to pull, call a trained electrician to assess the circuit breaker for malfunction.
  3. Call in an HVAC expert to test and replace a faulty furnace power control board. 

Burned Out Blower Motor

Your Goodman blower sends the heated air into your home through the ducts and vents. If the motor of the blower should burn due to wear and tear or electrical issues, then the blower will not work.

How to diagnose a burned out blower motor

If your blower motor is burnt out and cannot spin, it will produce a humming or buzzing sound when the furnace is turned on. Besides, it will not be blowing to send air to your home and will most likely produce a burning smell.

If you open the furnace cover and place your hand close to the blower behind the control board, the motor will feel extremely hot from the unsuccessful attempts to start.

How to fix a burned out blower motor

A burned-out blower motor will have to be replaced. Doing so means working with plenty of electrical wires, which is why you should call a trained HVAC technician to do the job. 

A Bad Furnace Capacitor

The capacitor sends the electrical signal to your motor so it can start running. If your Goodman furnace capacitor is bad, it will not send the signal and your furnace motor may keep asking for it in an effort to start blowing. 

How to diagnose and fix a bad furnace capacitor

Read details on how to diagnose and fix a bad Goodman furnace capacitor in the section on “Goodman Furnace Not Turning On.”

Goodman Furnace No Power to Thermostat

If your Goodman furnace’s thermostat is not receiving power, the thermostat is turned off, there’s no power supply, the thermostat fuse is blown, the thermostat is dirty, or the wires are loose or wrongly connected. No power supply to the thermostat is common but easily resolved by supplying power.

Thermostat is Turned Off

The first thing you should check if your furnace thermostat is not receiving power supply is if it is turned on. A thermostat that’s turned off will not be calling for power.

How to tell if your thermostat is turned off

Simply find the thermostat switch and see if it is on the off position

How to fix a furnace thermostat that’s turned off

Turn the thermostat switch from the off to the on position.

No Power Supply

Your furnace thermostat needs power to function, even though a thermostat may show signs of power when there’s a power outage because of the batteries, it cannot perform its main task of sending signals to the furnace. 

The main reason your Goodman furnace thermostat may not be receiving power supply is that there’s actually no power supply to your home from the utility line or the circuit breaker has tripped.

How to diagnose a thermostat with no power supply

You can test your thermostat with a multimeter if it appears that it’s not receiving power supply following these simple steps:

  1. Set your multimeter to the voltage option.
  2. Turn the meter dial to 24 volts (that’s the amount of voltage your thermostat needs to work).
  3. Touch the R terminal (usually where the red wire is attached) with one of the meter probes and the other probe to one of the other terminals. If the reading is between 22 and 26 volts, the thermostat has power. If the reading is 0, there’s no power flowing to the thermostat.

Alternatively, you can do simpler tests like turning on a bulb to see if it lights and opening the circuit breaker box to see if it is tripped.

How to fix furnace thermostat power supply issues 

Depending on the cause of power supply cut to your thermostat, talk to your area power supply company to have power restored or pull up a circuit breaker switch that has tripped to restore power. Always remember that a circuit breaker switch that’s hard to pull points to more complex electrical problems. In such instances, the circuit breaker should be assessed and repaired/replaced by a trained electrician.

Blown Thermostat Fuse

If your thermostat uses a fuse to regulate voltage, it could be blown and not send power supply.

How to diagnose a thermostat blown fuse

To tell if the fuse in your furnace thermostat is blown, assess it with the following steps:

  1. Open the outer casing of the thermostat. 
  2. Locate the fuse. A fuse looks like a glass tube with metal pieces on the extremes. 
  3. Check the filament inside the fuse for signs that it’s broken. This would mean it’s blown. Alternatively, the fuse glass will look stained if the fuse is blown,

How to fix a thermostat blown fuse

Purchase a new furnace fuse and replace the one that’s blown.

Loose or Wrongly Connected Wires

Loose thermostat wires or wires that are wrongly connected to the thermostat can mean no power flowing to your thermostat. On the control board, you have R, C, G, Y, and W terminals. The wires from each terminal need to be correctly plugged into the corresponding terminals on the thermostat.

How to diagnose loose or wrongly connected furnace thermostat wires

Check the thermostat wires to notice any loose ones and check your Goodman furnace User/Service Manual for an illustration on wiring the thermostat to make out if the connections are correct. 

Also, thermostat wires may be damaged or chewed through by mice or other pests. Check to ensure that this is not the case while you are at it.

How to fix loose or wrongly connected furnaces thermostat wires

Depending on the issue:

  1. Tighten any loose thermostat wires.
  2. Follow instructions on your Goodman furnace User/Service Manual to correct wrong furnace wire connections. ONLY DO THIS IF YOU ARE SURE YOU CAN DECIPHER THE INSTRUCTIONS CORRECTLY
  3. Replace/have a trained electrician or HVAC expert replace damaged thermostat wires.

Dirty Thermostat

This may sound odd but, if you’ve exhausted the above options and your thermostat is still not receiving power supply, you might want to check whether it’s covered with dirt and dust. This could insulate the electrical wire and ports, causing power not to flow.

How to tell if your furnace thermostat is dirty

It’s easy to tell if your furnace thermostat is dirty by simply opening it and noticing dirt and dust buildup.

How to clean a dirty furnace thermostat

To clean your dirty furnace thermostat:

  1. Open the outer casing of the thermostat.
  2. Use a can of compressed air to blow out the dirt and dust that’s build up in your thermostat. You can go for options that are 100% ozone-safe like the Falcon Dust-off Compressed Gas.
  3. Use a damp soft cloth to clean any remaining dirt.
  4. Replace the thermostat cover and wait a few minutes for any moisture from the moist cloth to dry out and then test to see if the thermostat starts to receive power supply.

As a concluding note, remember that it’s always safer to have an HVAC pro or a trained electrician resolve your Goodman furnace issues, especially if you are dealing with electrical furnace problems or you are not sure about the troubleshooting process. Safe heating!