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Furnace Ignitor Not Glowing? 4 Common Causes + What To Do

Every part of a furnace plays a role in allowing the device to heat up and distribute air throughout your home. The ignitor is the part that allows the furnace to increase the temperature of the air. One of the most common problems that people face with furnaces is an ignitor not glowing.

When the furnace ignitor is not glowing, it could be due to the ignitor itself. Other issues to look for are loose wires, problems with the control board, or an open rollout, limit, or pressure switch. 

This article will guide you through the troubleshooting and diagnostic steps to take when you find yourself in a situation with the furnace ignitor not glowing. We also offer several useful fixes and solutions. Our goal is to help you understand how you can get your ignitor to continue heating the air in your home. 

The Glow Plug May Need To Be Replaced

When the furnace ignitor is not giving off a glow, it could mean the glow plug has been damaged. The glow plug is an essential part of the ignitor. In cases where the glow plug is damaged, you may find no ignition when you start the furnace. This, of course, means there would also be no glow. 

Even though glow plugs are generally resilient, made to last a long time, damage can still occur. 

How To Fix

When a glow plug no longer functions normally, it is time for a replacement. This is one particular part of the ignitor that cannot be fixed. Thus, you will need to get a new glow plug and install it in the ignitor. 

The specific steps to follow when replacing the ignitor plug depend on the furnace model you have. You will usually need to open the ignitor compartment’s cover. Once this is open, you will find the glow plug inside. The plug is removed, and the new one is installed. 

Check for Dirt on the Ignitor

Over time, dust and dirt are sure to start collecting inside your furnace. Debris may also develop in certain areas of the device. While these particles’ collection is unlikely to cause major issues early on, it can lead to problems when you do not regularly clean the furnace’s interior. 

One particular problem that you may run into is dust behind the furnace ignitor not glowing. This can be due to dust making it harder for the sensor to work. Dirt collecting in the ignitor can also cause a blockage, which would then affect the ignition function. 

How To Fix

When dirt is the cause behind your ignitor not glowing, then there will not be a need for replacement parts. In most cases, you will be able to get the ignitor working again by simply cleaning the device. However, you should be cautious while cleaning, as you do not want to damage the interior of the furnace. 

Start by opening up the compartment cover where the ignitor is installed. When you are working inside the furnace, always switch it off first. This is a high voltage device, so you want to take your own safety into account. 

There are different parts of the ignitor system that should be cleaned. A good starting point would be the flame sensor. When this sensor has too much dirt on it, you may find that it interferes with your furnace’s functioning. 

If you are having trouble finding the sensor or cleaning it, take a look at this video: 

Make sure not to use any detergents or liquids when cleaning. You can use compressed air to blow dirt out of the ignitor, glow plug, and the flame sensor instead. 

The Ignitor Could Be Damaged

The ignitor itself is another element that you want to look at. When the ignitor is not glowing, it could be a sign that this particular part has been damaged. The ignitor generally handles a lot of pressure from the furnace. Even with frequent maintenance of your system, there is still a chance that the ignitor may become damaged over time. 

Different types of damage may cause the ignitor to stop working. Upon close inspection, you may find that the ignitor has a crack in it. Certain parts of the ignitor might be bent so that it no longer produces a spark for ignition. 

How To Fix

You first want to determine if the ignitor is damaged. You will need access to the furnace compartment with the ignitor. Remove the cover after switching the device off.

  1. Remove the ignitor and inspect it thoroughly. 
  2. Look for cracks in any part of the ignitor. 
  3. See if some parts of the ignitor are bent.
  4. Make sure there are no broken parts in the ignitor. 

If you find problems with the ignitor itself, you should consider getting a replacement for the part. It is usually best to just replace the ignitor instead of trying to fix the broken parts. 

Here’s a video that walks you through the steps to replace the igniter:

Gas Pressure Setting May Be Too Low

When you have a gas furnace, then you should look at the pressure of the gas inlet. When the furnace is turned on, gas is sent toward the ignitor. The ignitor then creates a spark, which leads to the ignition of the system. 

If insufficient gas levels are reaching the ignitor, it will not be able to do its job. This is often a problem that lies with the gas pressure. 

How To Fix

You will need to look at the gas inlet that is part of the furnace. Consider the current pressure setting of the gas inlet. This should give you an idea of whether there may be too little pressure to ensure the ignition process can occur without problems. 

There are a few scenarios to consider:

  • If the gas pressure is set to a low value, then the fix could be as simple as increasing the pressure setting. You will usually be able to turn a valve to increase the pressure coming from the gas supply.
  • If the pressure is at an adequate level, then there may be a leak somewhere in the gas supply. While the gas supply is turned on, follow the tubing used to push gas toward the ignitor. See if you can find any areas where gas is leaking. You will need to fix these leaks. Take note that loose valves can also cause gas to leak – in such a case, the solution would be to fasten the valve. 

Wrapping Up

A furnace ignitor not glowing may be caused by a damaged board, problems with the ignitor itself, or loose wires. When there is no glow on the ignitor once the furnace is turned on, you will find that your home is not heated up efficiently. Solutions can sometimes be simple, but it is important to understand the diagnostic process.