Hitachi Air Conditioner: Complete Troubleshooting Guide


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Comfort, convenience, high performance, and efficiency are all qualities used to describe Hitachi air conditioners. However, even the best air conditioner will give you trouble at some point, and Hitachi ACs are no exception.

That’s why I’ve put together this complete Hitachi air conditioner troubleshooting guide. In this guide, you’ll find explanations and solutions for every single problem your Hitachi AC might present. I’ll also mention when it’s best to skip the trouble and call an HVAC repair service instead of trying to fix the issue yourself.

Let’s get to it. This is a large guide, so I recommend that you use this table of contents to quickly jump to the issue your Hitachi AC is experiencing:

Potential Issues hide
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Hitachi Air Conditioner Not Cooling/Not Blowing Cold Air

If your Hitachi air conditioner is not cooling or blowing cold air, it may have the wrong temperature settings, the air filter or outdoor unit might be dirty, the thermostat might be detecting secondary heat, or the doors and windows might be letting out cold air and letting in hot air. You should clean your air filters regularly, as dirty filters are the most common cause of a lack of cooling in your Hitachi AC unit.

Incorrect Temperature Settings

Your Hitachi AC has operation modes that go from AUTO to HEAT to DEHUMIDIFY to COOL and FAN every time you press the mode button on the remote control. 

During the cooling season, you can work with the COOL or AUTO modes. 

The COOL mode on your Hitachi AC should be used when the outdoor temperature is between 21°C (69.8°F) and 43°C (109.4°F).

When the AUTO mode is used, the thermostat automatically adjusts the mode of operation between HEAT, COOL, and DEHUMIDIFY depending on the room temperature. Once the room temperature changes, the mode of operation changes automatically.

As such, if your Hitachi AC is set to the HEAT or DEHUMIDIFY mode, it’s not going to be cooling your house.

How to Diagnose Hitachi AC Incorrect Temperature Settings (Cooling Mode)

Simply check your Hitachi AC thermostat to notice the current mode that the AC is operating on and adjust it to the COOL mode. .

How to Fix Hitachi AC Incorrect Temperature Settings (Cooling Mode) 

Use the function selector button to move between the different operation modes until you can select the COOL or AUTO mode as desired. If you choose the COOL mode, set your desired temperature using the increase and decrease options of the TEMPERATURE button until you can see the desired temperature on the display screen.

Dirty Air Filters

A dirty air filter is the most common cause of inefficiency in your cooling system. Luckily, it is also easy to resolve.

The Hitachi AC manufacturer recommends that you clean your AC’s air filter every 15 days. If you don’t clean your filters regularly, you’ll likely experience some of the following problems:

  • Poor airflow in and out of the unit.
  • Low cooling capacity.
  • A musty smell when the AC is on.
  • Overheating.
  • Increased energy bills.
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How to Diagnose a Dirty Hitachi AC Air Filter

To check whether your Hitachi AC air filter is dirty, ensure that the indoor unit is turned off and open the front panel by holding both sides and allowing the panel to swing upwards. This reveals the filters and you can easily tell if they are covered with dirt. If that is the case, proceed to clean the air filters.

Note that your Hitachi AC filter indicator lamp (green) will also come on when a dirty air filter is detected or your AC has run for 200 hours without cleaning the filter.

How to Clean a Dirty Hitachi AC Air Filter

Use these instructions from the Hitachi AC manufacturer to clean dirty air filters:

  1. Switch off your Hitachi AC.
  2. Hold the front panel with both hands from each side and allow the panel to swing upwards, then pull towards you to remove it.
  3. Remove the air filters by pulling them towards you.
  4. Use a vacuum cleaner to remove the dust from the air filter and proceed to wash with a mixture of warm water and a little kitchen detergent, then rinse thoroughly as detergent left on the filter can make it deteriorate with time. Ensure the water is not warmer than 40°C (104°F) to avoid damaging the air filter.
  5. Shake off the excess water from the filter and leave it to dry under the shade (never under direct sunlight).
  6. Reinstall the dry filters back in place, ensuring that the ‘FRONT’ mark is facing front.
  7. Replace the front panel and switch the AC back on to resume operation.

You can watch this quick video demonstration on How to clean the filter of a Split Air Conditioner by Hitachi. Note also that if your Hitachi air conditioner has a stainless steel-coated air filter, you can use the Auto Filter Clean Technology (iClean) feature on your remote control to clean the air filter automatically as shown in this video.

Dirty Outdoor Unit

A dirty Hitachi AC outdoor unit compromises airflow and the regulation of temperatures in the cooling process. Plant matter, dust, and other forms of dirt and debris can all stay on the way of air going in and out of your AC and block in heat, causing poor or no cooling inside your home.

How to Diagnose a Dirty Hitachi AC Outdoor Unit

How easily you can check whether your Hitachi AC outdoor unit is dirty will depend on its location. If the outdoor unit is on ground level, you can easily unscrew the top cover and look inside to notice dust and debris buildup. If the outdoor unit is installed on the wall of a high-rise building or apartment, you’ll require the services of an HVAC expert.

How to Clean a Dirty Hitachi AC Outdoor Unit

The outdoor Hitachi AC unit houses the fan, compressor, condenser coil, and electrical parts. Focus on the condenser and fan when cleaning your Hitachi AC outdoor unit and follow these steps:

  1. Switch off the AC from the circuit breaker and wait 30 minutes for it to cool. 
  2. Unscrew the top cover of the outer casing, the air discharge grille, and the front panel in that order. This should reveal the condenser, fan, and electrical components. 
  3. Remove any loose plant matter and debris by hand while paying attention not to be cut by the coil fins.
  4. Use a low-pressure hose to spray water on the fan and condenser coil. If there’s plenty of dirt on the fins, use a soft brush to scrub off stubborn dirt by making up and down strokes only. Ensure you do not bend any fins out of position as this will compromise airflow into the unit. Also, be careful not to send any water to the compressor or electrical parts. This could cause an electrical shock when the unit is turned back on.
  5. Wash the panels of the outer casing and air grill while waiting for the condenser and fan to dry completely. You can also use a damp and soft cloth to dust inside the panels of the compressor and electrical compartment but stay attentive not to cause any damages.
  6. When the outdoor unit is dry, screw the outer casing back in place, starting with the front panel, the air inlet grill, and the top panel last. Ensure all screws are put back and tightened. A loosely fit outdoor unit casing will make noise when the cooling unit is operating.
  7. Turn the AC back on and resume operation.

If your Hitachi AC outdoor unit is mounted on a high wall or you are not sure you can complete the cleaning procedure without causing damage, call a reliable HVAC expert to do professional cleaning on the outdoor unit. We can send you a certified Hitachi AC expert to clean your outdoor unit as soon as you fill and submit the form at the bottom of this article.

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Bad Thermostat Position

An AC thermostat is temperature sensitive, which is why it detects and displays the current temperature in your room. If the thermostat is installed in a location that receives cool air from other secondary sources such as a freezer, cooling room, or cool air ducts, the thermostat will consistently give erroneous temperature numbers, causing your AC to stay off or turn off earlier while the other areas of the room are warmer.

How to Diagnose Bad Thermostat Position

Remove the secondary source of cool air and see if the thermostat begins to reflect the actual room temperatures and if the AC resumes normal cooling cycles, meaning your AC blows cold air as it should.

How to Fix Bad Thermostat Position 

If the secondary source of cool air is removed and the thermostat and AC begin to function as they should, reposition the thermostat to a central part of the room where the room temperature is not tampered with by secondary cool air. This should normalize your Hitachi AC cooling cycles. 

Fluctuating Season Temperatures

During the transition period between seasons, outdoor temperatures may fluctuate for weeks. This could disrupt the working of your AC, causing it to short-cycle or run for longer cycles depending on the temperature fluctuations.

What to Do During Fluctuating Season Temperatures

Hitachi manufacturers recommend that you set your AC to the COOL mode only when the outdoor temperatures are consistently above 21°C (69.8°F).

In fluctuating temperatures instead, opt for natural ventilation options such as opening doors and windows to keep your home cooler.

Poor Cold Air Distribution/Blocked Indoor Unit Airway

If your Hitachi AC is doing its air-cooling job but the cool air is getting trapped or is poorly distributed, it may appear as though your cooling unit is not blowing cold air. 

This could be caused by furniture that’s standing in the way of cool air or by blocked return and supply air vents. According to Pacific Gas and Electric Company (PGE), blocked air vents make your cooling system work harder than it should, requiring up to 25% more energy to distribute cool air.

How to Diagnose Poor Cold Air Distribution/Blocked Indoor Unit Airway

Check to see if any furniture or drapes are standing in the way of cold air from your indoor unit. Also, inspect the ductwork for any signs of blockage or leaks.

How to Fix Poor Cold Air Distribution/Blocked Indoor Unit Airway

Remove any objects that are blocking the airway of your Hitachi AC indoor unit or obstructing the distribution of cold air from the air vents. Any large objects in front of air vents should be at least 10ʺ away (further away is better).

Open Door and Windows

Open doors and windows are not only an outlet for cooled air but also an inlet for warm air from the outdoors. Ensure that doors and windows are closed and are without air leaks during the cooling process.

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Hitachi Air Conditioner Not Responding To Remote Control

If your Hitachi AC is not responding to the remote control, the control board could be faulty or the thermostat sensor dead. These are not common AC problems but, when they happen, they are best addressed by a professional HVAC technician.

Faulty Control Board

Your Hitachi air conditioner control board has a receiver for signals from the remote control. If the control board is faulty due to a short circuit or other electrical defects, the signal receiver will not work and the commands from the remote control will not be effected.  

How to Diagnose and Fix a Faulty Hitachi AC Control Board

Control boards are power control and signal centers of your Hitachi AC. As such, any signs of a malfunction should be assessed and resolved by a certified Hitachi HVAC pro and not by trial and error troubleshooting.

The HVAC pro will replace a faulty AC control board. We can connect you to a professional Hitachi AC pro as soon as you fill and submit the form at the bottom of this article.

Dead AC thermostat Sensor

To receive signals from the remote control, your Hitachi AC thermostat has a sensor that detects commands from the remote. If this sensor is dead or defective, your AC will not be responding to the remote control commands. 

How to Diagnose and Fix a Dead AC Thermostat Sensor

If your remote control shows signs that it’s working but the commands are not getting to the AC, find the AC’s thermostat sensor near the cooling coil and check whether it has moved out of its usual position or if the wires are broken.

This may not be a straightforward troubleshooting fix and you are better off calling a trained HVAC pro to assess and repair/replace a faulty or dead thermostat sensor.

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Hitachi Air Conditioner Not Turning On

A Hitachi air conditioner that’s not turning on could have power supply issues (unplugged cable, dead wall plug, a strained wall plug, damaged cable, and utility power outage) or a tripped circuit breaker. An unplugged power cable/switch not turned on is more common and should be checked first.

Power Supply Issues

Your Hitachi AC needs a stable power supply to run efficiently. If this is not the case, the cooling unit will not turn on. 

Power issues that cause your Hitachi AC not to turn on include:

  • An unplugged AC cable.
  • A dead wall outlet.
  • A strained electrical wall plug.
  • A damaged AC power cable.
  • Utility power outage.

How to Diagnose Hitachi AC Power Issues

Depending on the issue, check the following:

  • Check first that the Hitachi AC cable is plugged in and the switch turned on.
  • Test the wall outlet you are using with the AC for voltage by plugging other appliances to see if they turn on.
  • Check to ensure that the electrical wall outlet where you’ve plugged your AC is not strained. Electrical wall plugs should take a standard voltage load of around 1,800-2,400 watts. So, if for example, your AC is already taking 1,500watts, another appliance in the same plug will likely cause an overload.
  • Check your Hitachi AC power cable for damage by noticing any physical signs of threadbare parts or breakage. If the cable is intact, test it for continuity with a multimeter. If the cable has continuity, it will make a beep when you touch the prongs of the AC end of the power cord with the multimeter test probes. If there’s no beep, the power cord is open and does not transmit current.
  • Turn on a bulb or other electrical appliances in the home to see if there’s a power outage.
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How to Fix Hitachi AC Power Issues

Depending on the issue, perform the following to avoid power issues with your Hitachi AC:

  • Plug in and switch on a Hitachi power cable that is not plugged in and turn on the power switch.
  • Call a trained electrician to repair/replace a dead power outlet.
  • Ensure you do not plug your Hitachi AC into a wall outlet with other appliances using a power adapter or electrical extension. These power extensions can have lower voltage capacity and cause an overload or short circuit.
  • Contact your Hitachi AC dealer about a damaged AC cable so it can be replaced or contact the Hitachi Maintenance and Support Partner Centre by calling this number: (800) 446-0744
  • Enquire about power outages with the utility company in your area to speed up the restoration of the power supply.

Tripped Circuit Breaker

If your Hitachi air conditioner does not show signs of activity when turned on, check whether the circuit breaker has tripped. 

A tripped circuit breaker means that the power supply is abruptly cut off due to a power surge on your AC’s line or an operational strain due to dirty air filters.

If this happens, the power supply to your Hitachi AC will not be resumed until you turn back the power on at the circuit breaker.

How to Diagnose a Tripped Circuit Breaker

Open the circuit breaker box and check if the switch that supplies power to your AC is turned on (up position) or off (down position).

If the switch is down, then the circuit is tripped and needs to be turned back on.

How to Fix a Tripped Circuit Breaker 

Slowly push the tripped switch up to turn it back on. Ensure that you are not forcing the switch back on as this could mean more serious electrical issues. If the switch is hard to turn back on, call a trained electrical expert to assess issues with the circuit breaker or replace it if need be.

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Hitachi Air Conditioner Keeps Turning Off

If your Hitachi air conditioner keeps turning off, the power supply is unstable due to frequent power surges or short circuits, there’s a faulty plug, a loose cable, or faulty electrical wires. Uncommon causes like a faulty thermostat, refrigerant issues, or an oversized AC could also be the cause.

Note that air conditioners are meant to cycle every 10-15 minutes. But if the AC has shorter cycles than this or often turns off completely, then one of the following issues could be the cause.

Unstable Power Supply 

An unstable power supply to your AC is the most probable reason your Hitachi AC will keep turning off when it shouldn’t. This could be caused by one of these problems:

  • Regular power surges or short circuits.
  • A faulty wall outlet plug.
  • A loose power cable.
  • Defective electrical wires of the compressor, thermostat, fan/fan motor, or control board.

How to Diagnose Hitachi AC Unstable Power Supply Issues

Assess your Hitachi AC’s power supply by:

  • Noticing if the circuit breaker trips regularly.
  • Plugging the AC power cable into a different wall outlet if you suspect that the one in use is faulty.
  • Firmly plugging a loose power cable.
  • Using a multimeter to test AC-part wires for continuity (if you are up to the task, otherwise call an HVAC expert or a trained electrician).

How to Fix Hitachi AC Unstable Power Supply Issues 

While you can fix a loose cable so that it is firmly plugged into the wall outlet, the safest bet when it comes to other AC power issues is to have a trained electrician or a professional HVAC technician assess and resolve the issue.

We can send you a reliable Hitachi AC pro to help you with your AC power issues as soon as you fill and submit the form at the bottom of the article.

A Defective AC Thermostat

This may not be a common problem with your Hitachi AC but, when it happens, it compromises the working of your entire cooling system. Since the thermostat controls the start and end of the cooling cycles, a faulty one will disrupt normal cooling cycles, which could mean that your AC keeps turning off.

How to Diagnose a Defective Hitachi AC Thermostat

If your Hitachi AC thermostat is displaying extremely high or low temperatures, that could be a sign that it is faulty and not working normally.

Check also if your AC thermostat tends to switch off automatically when it should not as this could be a sign it has power supply issues.

How to Fix a Defective Hitachi AC Thermostat

Temperatures on your Hitachi AC thermostat may fluctuate abnormally if the thermostat is exposed to secondary heat or cold. If that is not the case, the thermostat may be defective and needs to be replaced. 

Call an expert Hitachi AC pro and let them determine if our AC thermostat is indeed faulty, then proceed to replace it with a new one.

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Refrigerant Issues

The refrigerant in your Hitachi AC disperses the heat produced during the cooling process. If your AC has low refrigerant levels due to a leak, heat absorption is compromised. This causes the compressor’s pressure levels to be altered and can lead to shorter cooling cycles, which is why your AC will keep turning off.

How to Diagnose Hitachi AC Low Refrigerant Levels

A short-cycling air conditioner is one of the signs of an AC with low refrigerant levels. Other possible signs to look for include:

  • Cooling coils that keep freezing up.
  • An AC that’s not cooling enough.
  • An overworked and noisy compressor.
  • Higher electricity bills during the cooling season.

How to Fix Hitachi AC Low Refrigerant Levels 

A trained HVAC technician should assess and resolve AC refrigerant issues. So, if your AC keeps turning off and all the other possible causes have been eliminated, call in an HVAC pro to perform the following: 

  1. Assess if your Hitachi AC has the correct Freon levels.
  2. If the Freon levels are faulty, the HVAC will advise you if the refrigerant recharge procedure is cheaper than purchasing a new AC, especially if you have an old unit.
  3. If Freon-recharge is advised, the HVAC expert will evacuate the AC of the existing refrigerant until the acceptance value is obtained.
  4. Charge the AC with fresh Freon up to the specified levels.

Fill and submit the form at the bottom of this article and let us help you by sending a reliable Hitachi AC pro to attend to your AC’s refrigerant issues.

An Oversized AC

Homeowners sometimes think that having a big AC will cool or heat their home faster. While this is actually the case, it does not, however, mean effective cooling or heating.

An oversized Hitachi AC has a BTU rating bigger than what you need for the space you want to be heated. What happens, in this case, is that your AC will indeed produce cool air faster, but the distribution of the cooled air happens poorly. 

As a result, the cool air around the AC is detected as the prevailing temperature for the entire space, and the AC keeps turning off in shorter cycles.

How to Diagnose an Oversized Hitachi AC

To understand if your Hitachi AC is oversized, compare its BTU rating with the size of the space you are cooling following this procedure:

  1. Check your Hitachi BTU rating from the label plate.
  2. Calculate the size of your room in square feet (length x width).
  3. Check how many BTUs are needed to cool the size of the room you just calculated. You can check this from Energy Star Room Air Conditioner Buying Guide

If your Hitachi AC BTU rating is higher than what you need for the size, then it is oversized. 

For example, if your Hitachi AC is rated for 10,000 BTU/Hr, and your room is only 300 square feet, then the AC is oversized. An AC rated 7,000 BTU/Hr would be sufficient for such a space.

How to Fix an Oversized Hitachi AC

The only way to fix an oversized Hitachi AC is to replace it with one that is the right size for your space. While this may sound like a costly move, it will eventually save you from poor cool air distribution and a short-cycling AC, and most especially from unnecessary power bills.

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Hitachi Air Conditioner Leaking Water

If your Hitachi air conditioner is leaking water, the drain line is blocked, or the cooling coil is frozen. A blocked drain line is the most common cause of a leaking AC and should be resolved by unclogging the drain line.

Blocked Drain Line

Dirt and dust accumulation in an AC’s drain pipe or the main drain line can cause water to stay in the drain pipe and drain pan and eventually overflow, causing a leak. 

How to Diagnose a Blocked AC Drain Line

A blocked AC drain line is easy to diagnose as there are several observable signs that come with it: 

  • An overflowing AC drain pan.
  • A moldy smell around the cooling unit and from the air vents.
  • A dry outdoor drain line outlet.
  • Dirt from the drain line when a wire or drain snake is inserted into the drain line.

How to Unclog a Blocked AC Drain Line

To clear an AC drain line of blockage, perform the following: 

  1. Switch off the AC.
  2. Use a sponge or soft rag to collect the standing water from the drain pan and squeeze it into a bucket. If your AC’s drain pan has a drain hole, remove the stopper and let the water flow into a bucket. 
  3. Use a shop vacuum to suck out the water standing in the AC’s drain pipe. If you can’t do that, let the water flow out when you unclog the drain line.
  4. Pull out any dirt that’s stuck in the drain line using a piece of long wire or a drain snake.
  5. Once the drain line is clear, throw a mixture of warm water with a bit of vinegar and kitchen detergent into the drain line to clear any dirt stuck on the pipes.
  6. Turn the AC back on and resume operation. Monitor to ensure that the AC is not leaking anymore.

Frozen Evaporator Coil

Poor airflow is the main reason your Hitachi AC evaporator coil freezes up. Compromised airflow is especially caused by dirty air filters, but will also result from blocked airways, a defective fan blower, leaking ductwork, or a dirty evaporator coil.

If the ice is melting and sending extra water to the drain pan so that the drain pipe cannot send it out through the drain line as fast as needed, the cooling unit will start leaking.

How to Diagnose Frozen Hitachi AC Evaporator Coil

You can tell if your Hitachi AC is frozen if there are water droplets on the outer casing of the indoor unit.

To check the evaporator coil for ice, follow these steps:

  1. Switch off your Hitachi AC.
  2. Hold the front panel with both hands from each side and allow the panel to swing upwards, then pull towards you to remove it.
  3. Remove the filters by pulling them towards you. The evaporator coil will then be revealed.
  4. Check to see if the evaporator coil is covered with ice.
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How to Fix Frozen Hitachi AC Evaporator Coil

If there’s ice on your Hitachi AC evaporator coil, leave the AC turned off so the ice can melt. If you want to speed up the melting process, set the AC on High fan speed for about 15 minutes.

You’ll also need to find out the cause of frozen evaporator coils and address the problem so the coil does not freeze up again. 

Note that the Hitachi manufacturer advises that you call a professional HVAC any time you notice a leak from your indoor unit.

Hitachi Air Conditioner Not Heating

If your Hitachi air conditioner is not heating, the temperature settings are wrong or you have an undersized air conditioner. Wrong AC settings are the most common cause of a Hitachi AC not cooling, which can easily be solved by correcting the settings.

Incorrect Temperature Settings

When you have a reverse cycle Hitachi air conditioner, you can use the HEAT or AUTO mode to heat your space in the cold season. 

Use your Hitachi AC in the HEAT mode when the outdoor temperature is below 21°C (69.8°F). Your AC may not heat if the temperatures are above this level as an auto-protection function.

When the AUTO mode is used, the thermostat automatically adjusts the mode of operation between COOL, HEAT, and DEHUMIDIFY depending on the room temperature. Once the room temperature is reached, your AC will automatically start heating in the cold season.

How to Diagnose Hitachi AC Wrong Temperature Settings (Heating Mode)

Check that your Hitachi AC is set on the HEAT or AUTO mode as desired and not on the COOL or DEHUMIDIFY mode. 

How to Fix Hitachi AC Wrong Temperature Settings (Heating Mode)

Use the Function selector button to move between the different operation modes until you can select the HEAT or AUTO mode as desired. If you choose the HEAT mode, set your desired temperature using the increase and decrease options of the TEMPERATURE button until you can see the desired temperature on the display screen.

Also, set your Fan speed to HI as this will warm the room faster. If the Fan speed is set to AUTO, it will start at HI and gradually move to MED and LOW speeds when the set temperature is reached.

Undersized Air Conditioner 

When buying your Hitachi air conditioner, it is important to check its cooling and heating capacity and establish if it is enough for the space you want to heat or cool.

If you purchased a Hitachi reverse cycle AC that has a lower heating capacity than you require, you’ll always feel like your air conditioner is not doing its heating work because the hot air will never be enough.

How to Diagnose an Undersized Hitachi AC

To know if your Hitachi AC is undersized, compare its heating capacity (in BTU/Hr) with the size of the space you are heating following this procedure:

  1. Check your Hitachi heating capacity in BTUs from the label plate.
  2. Calculate the size of your room you are going to heat in square feet (length x width).
  3. Check how many BTUs/Hr are needed to heat the size of the space you just calculated. You can check this from Energy Star Room Air Conditioner Buying Guide

If your Hitachi AC has a heating capacity that’s lower than what you need for the space size, then it is undersized. 

For example, if your Hitachi AC is rated for 10,000 BTUs/Hr, and your space is 700 square feet, then the AC is undersized. You would need an AC with a 14,000 BTUs/Hr rating to heat a 700 square feet space.

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How to Fix an Oversized Hitachi AC

There are two ways you can resolve the problem of an undersized Hitachi AC for heating:

  1. Purchase a window or portable air conditioner with a BTU rating that’s equal to the missing amount of heating energy required for your space to supplement the heat deficit.
  2. Purchase a new AC with a BTU rating that’s sufficient for the space you want to heat. This may be costly at first but it will save you money in power bills later (you do not have to run two appliances at the same time as with the first option or make the AC overwork to be able to heat the space).

Hitachi Air Conditioner Remote Not Working

If your Hitachi air conditioner remote is not working, the remote control batteries are dead, the batteries’ polarity is reversed, the remote is damaged, or the remote is being used from a long control range. Dead batteries are the most common cause for a remote not working and should be replaced.

Dead Remote Control Batteries/Reversed Battery Polarity

Your Hitachi AC remote control uses AAA batteries. If these are low on charge (below 1.3v), they will not provide the required charge to send commands to your AC.

Also, if the batteries are inserted in a way that their polarities are reversed, the remote control will not function.

How to Diagnose Dead Remote Control Batteries/ Reversed Battery Polarity

Test the batteries of your Hitachi AC remote control with a voltmeter to ensure they have a voltage charge higher than 1.3v. 

Ensure that the batteries in your Hitachi AC remote control are inserted with polarities in the right position (+ve with +ve and -ve with –ve).

How to Fix Dead Remote Control Batteries/ Reversed Battery Polarity

Replace remote control batteries if they have a voltage lower than 1.3. Follow these instructions on how to replace your Hitachi remote control batteries:

  1. Remove the cover at the rear of your Hitachi remote control by pushing it in the direction of the arrow. 
  2. Remove the old batteries.
  3. Insert the new batteries, making sure to follow the polarity indications (+ve with +ve and -ve with –ve).
  4. Place back the remote control cover.

Note: Do not mix old and new batteries or different types of batteries. Also, remove batteries from the remote control when the AC is not in use for more than 2 months.

Damaged Remote Control

If your Hitachi AC remote control has been dropped or sprayed with water, the signal transmission quality may be lost or reduced.

A remote control whose sensor is damaged due to a broken wire will also not send signals to your AC.

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How to Diagnose a Damaged Hitachi AC Remote Control

The first sign of a damaged Hitachi remote control is that it won’t send signals to your AC. Besides, the sensor light will not go on as it should when commands are given.

Use the temporary switch on the indoor unit to start or stop cooling operation. If this works but does not with the remote control, then the remote control is damaged.

How to Fix a Damaged Hitachi AC Remote Control

Replace a damaged Hitachi AC remote control. Fixing a damaged one may cost more than purchasing a new one.

Long Control Range

To effect commands on your Hitachi AC, the remote control must be within a 7-meter (23 feet) control range. If it’s further than this, the commands will not be delivered to your AC.

How to Diagnose and Fix Hitachi AC Long Remote Control Range

Try sending commands to your AC from a closer range and see if the cooling unit responds to the remote control.

If this does not work, the remote control or AC remote sensor could be faulty. 

Note that your Hitachi remote control may fail to function if your room lighting is electronically controlled as this shortens the remote’s range of control.

Hitachi Air Conditioner Light Blinking

Blinking lights in your Hitachi AC can be normal function alerts as in the case of yellow light blinking that shows preheating or defrosting or the green light blinking that’s an air filter alert. Blinking Hitachi AC lights can also show malfunctions like defective AC parts or faulty connections.

Hitachi Air Conditioner Yellow Light Blinking

The Yellow Light in your Hitachi air conditioner is the Operation Lamp. This light is always lit during operation but will blink during heating when:

  1. Your Hitachi AC is Preheating (2-3 minutes when the Heat mode is turned on).
  2. Your Hitachi AC is Defrosting. This happens once every hour when frost has formed on the AC’s outdoor unit heat exchanger and lasts for 5-10 minutes.

Both processes are not malfunctions per se. Allow the processes to take their course and your Hitachi AC will resume normal operation once the processes are complete.

Hitachi Air Conditioner Flashing Timer Light

The Hitachi AC Timer Light (orange) is always lit when the timer is set. This light will flash with variation in several situations: 

Hitachi AC Timer Light Flashing x 1

When the Hitachi AC timer light flashes x 1, the indoor heat exchanger temperature is too high in the cooling mode or too low in the heating mode. The timer lamp begins flashing when the malfunction is detected for a 3rd time during the normal 3-minute interval reading.

Hitachi AC timer light flashing x 1 malfunction can be caused by:

  • A defective reverse valve.
  • A disconnected heat exchanger thermistor during the heating mode.

Call a certified Hitachi AC pro to address the issue.

Hitachi AC Timer Light Flashing x 2

If your Hitachi AC timer light is flashing x 2, the outdoor unit is under forced operation or is balancing operation after forced operation. This is caused by faulty electrical parts in the outdoor unit.

Call a certified Hitachi AC pro to address the issue.

Hitachi AC Timer Light Flashing x 3

When your Hitachi AC timer light flashes x 3, the indoor or outdoor unit’s interface is defective. This happens when the outdoor unit interface signal is interrupted.

Hitachi AC timer light flashing x 3 can be caused by:

  • A defective indoor unit interface circuit.
  • A defective outdoor unit interface circuit.

Call a certified Hitachi AC pro to address the issue.

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Hitachi AC Timer Light Flashing x 4

Hitachi AC timer light flashing x3 can be caused by defective components in the outdoor unit. The flashing begins when the malfunction has been detected 8 times in 30 minutes.

Check the AC’s self-diagnosis display on the outdoor unit for details and call a certified Hitachi AC pro to address the issue.

Hitachi AC Timer Light Flashing x 9

If your Hitachi AC timer light flashes x 9, the room thermistor or heat exchanger thermistor is defective. 

Hitachi AC timer light flashing x 9 can be caused by:

  • An open or short-circuited room thermistor.
  • A short-circuited or open heat exchanger thermistor.

Call a certified Hitachi AC pro to address the issue.

Hitachi AC Timer Light Flashing x 10

When the Hitachi AC timer light is flashing x 10, the DC fan motor is overcharged. This can be caused by:

  • A locked indoor fan.
  • A faulty indoor fan motor.
  • A defective indoor power control board.

Call a certified Hitachi AC pro to address the issue.

Hitachi AC Timer Light Flashing x 13

When the Hitachi AC timer light flashes x 13, there’s a data reading error. Call a certified Hitachi AC pro to address the issue.

Hitachi Air Conditioner Temporary Switch Flashing

When your remote control is not working, the temporary switch is used to start or stop the AC. Using the temporary switch to start your Hitachi AC resumes the latest setting.

If the remote control is used again after the temporary switch has been used, the temporary AC starts flashing. Simply press the temporary switch again to resume operation with the remote control.

Hitachi Air Conditioner Flashing Red Light

If your Hitachi AC red light is flashing, one of these situations is happening:

  • The cable is not connected properly.
  • The terminating resistors are not connected properly.
  • The cable connector is loose or almost falling off the mating connector of the D.Station module.

Consult the Hitachi Troubleshooting Manual or call a certified Hitachi AC pro to perform the following:

  1. Connect the cable properly.
  2. Connect the terminating resistors properly.
  3. Insert the connector firmly into the mating connector.

Hitachi Air Conditioner Green Light Blinking

The Green light in your Hitachi AC is for the Filter lamp. This light blinks when your AC has run for 200 hours as an air filter cleaning alert.

You can press the Auto Swing button to stop the blinking, but the best solution is to clean your AC’s air filter.

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Hitachi Air Conditioner Error Codes/Fault Codes

Hitachi AC error codes are error signals (also fault codes or alarm codes) are error signals that Hitachi air conditioners produce when technical defects like the EEPROM data error, the absence of voltage, a communication fault, or a frozen AC are detected in the appliance.

The function of error codes in your Hitachi AC is to let the servicing technician (not the user) know what problem your cooling unit has and thus facilitate the resolution of the problem. 

As a rule, Hitachi AC error codes should be resolved by a certified Hitachi HVAC pro. Here are some of the most common Hitachi AC error codes.

Hitachi AC Error Code 4 Time Blinking

Hitachi AC Error Code 4 time blinking is an “EEPROM data error.” EEPROM means Electrically Erasable Programmable Read-Only Memory which is a data storage space containing codes in your AC.

This error code can be triggered by one of these problems in your cooling system:

  • EEPROM components failure.
  • EEPROM components circuit failure.
  • EEPROM incorrect components’ inserting.

How to Resolve Hitachi AC Error Code 4 Time Blinking

Call a certified Hitachi AC pro to:

  1. Assess the EE components for faults and replace them if needed.
  2. Replace faulty components of the outdoor unit control board.
  3. Reassemble failed EE components.

Hitachi AC Error Code 5 Time Blinking

Hitachi AC Error Code 5 time blinking is a “cooling freezing protection” code. It means that the indoor coil temperature is too low (during cooling) or too high (during heating).

Error Code 5 in your Hitachi AC happens when:

  • The indoor unit is not blowing air normally.
  • The room temperature is too low.
  • The air filter is dirty and limiting airflow.
  • The duct resistance is too high, resulting in low airflow.
  • The fan speed is set too low.
  • The indoor unit is not properly installed (the air inlet is too close to the air outlet).

How to Fix Hitachi AC Error Code 5 Time Blinking

You can clean your Hitachi AC air filters and set the fan on high speed to see if the error code 5 time blinking is resolved. 

If not, call a certified Hitachi AC pro to:

  1. Check the indoor fan, fan motor, and evaporator coil for faults.
  2. Perform a maintenance cleaning on your AC.
  3. Assess the volume control valve and the duct length for faults.
  4. Properly reinstall the indoor unit while referring to the installation guidelines on the User Manual.
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Hitachi AC Error Code 7 Time Blinking

Hitachi air conditioner Error Code 7 time blinking is a “communication fault between the indoor and the outdoor units.”

Error Code 7 on your Hitachi AC can be caused by one of these issues:

  • Wrong cable connection between the indoor and the outdoor unit.
  • A loosely connected indoor-outdoor unit cable.
  • A faulty indoor-outdoor unit connection cable.
  • Faulty indoor or/and outdoor unit control board.
  • An open communication circuit fuse.
  • A communication cable with wrong specifications.

How to Fix Hitachi AC Error Code 7 Time Blinking

Call a certified Hitachi AC pro to:

  1. Reconnect a loose or wrongly connected communication cable while referring to the wiring diagram.
  2. Replace a faulty communication cable.
  3. Replace a faulty indoor or/and outdoor control board.
  4. Check if the communication circuit fuse is open and adjust it in case of a short circuit.
  5. Provide the correct communication circuit cable by referring to specifications on the User Manual.

Hitachi AC Error Code 9 Time Blinking

Hitachi AC Error Code 9 time blinking is a “U phase current fault” that happens with 3-phase power supply Hitachi AC models.

Error Code 9 in your Hitachi AC will happen in these conditions:

  • Wrong connection of the compressor U phase power cord.
  • A faulty compressor U phase power cord.
  • A faulty outdoor unit control board.
  • A faulty compressor.

How to Fix Hitachi AC Error Code 9 Time Blinking

Call a certified Hitachi AC pro to:

  1. Replace a faulty U phase power cord.
  2. Correct a wrongly connected U phase power cord by referring to the wiring diagram in the User Manual.
  3. Assess and replace a faulty outdoor unit control board.
  4. Assess and replace a faulty compressor.

Hitachi AC Error Code 12 Time Blinking

Hitachi air conditioner Error Code 12 time blinking is a “voltage absent phase” occurring in 3-phase power supply Hitachi AC models.

Error Code 12 in your Hitachi AC can be caused by these problems:

  • Abnormality in the 3-phase power.
  • Wrong outdoor unit wiring.
  • Malfunctioned outdoor unit.

How to Fix Hitachi AC Error Code 12 Time Blinking

To fix error code 12 on your Hitachi AC, call a certified Hitachi AC pro to:

  1. Check the outdoor unit wiring and correct faults while referring to the wiring diagram on the User Manual.
  2. Assess and replace a malfunctioned outdoor unit.

Note that Hitachi AC error codes may vary with AC models. Besides, some error codes like Hitachi AC Error Code E9 may not be found in User Manuals or Service Manuals accessible to the public, which is why you should always call a certified Hitachi AC pro. To find a local HVAC repair expert near you, just click the button below this sentence.

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Vincent Steele

Vincent is a freelance writer based in Santa Ana, California. When he isn't writing articles for Temperature Master, he can be found biking or hanging out with his cat, Shelly.

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