Why Furnace Ignitor Lights but No Flame? How To Troubleshoot?

If there is no flame in your furnace, then your house won’t be receiving any heat. And that will, of course, become a huge problem, especially, on a cold winter day.

When your furnace ignitor lights but there is no flame it usually means that there is an issue with the gas valve or the ignitor is not able to get hot enough. Make sure that there is a gas supply and 24V to the gas valve and that the ignitor is clean.

Furnace Ignitor Lights but No Flame

If your furnace ignitor lights, but no flame appears, the chances are high that the root cause is either the gas valve or the actual ignitor.

Issues with the gas valve

Once the ignitor heats up to a certain temperature, the gas valve opens. If the valve stays closed, the main burner will not ignite.

You would have to make sure that there is gas available at the gas valve and that the element is receiving 24V. If there is gas and power, you might have to replace the gas valve.

Also, do bear in mind that if the pressure in the system is way too high the gas valve will lock itself up.

Read: Furnace Clicks But Doesn’t Turn On – Troubleshooting Guide

Issues with the ignitor

Only once the ignitor gets hot enough, the gas valve will open. At times, the element might simply be too weak and incapable of producing enough heat.

This can happen if the ignitor is dirty or if the ignitor remained on even after the gas was activated (this might have affected the element’s lifespan).

Usually, the simplest fix is to replace the ignitor. Such a component is relatively cheap and you don’t need to be an HVAC expert in order to replace it.

Read: Is It Ok To Have A Furnace In The Crawl Space?

Amana Furnace Ignitor Glows No Flame

While the ignitor is glowing, test the gas valve for 24V.

If the reading shows 24V, then the gas valve had gone bad. If you’re not getting 24V at the valve, then there is either a bad connection between the valve and the control board or the board is faulty.

The issue can also be with the gas pressure to the gas valve.

Coleman Furnace Igniter Glows but No Flame

If your furnace isn’t able to ignite the flame, then make sure to check the gas supply. Simply check another gas appliance in the house – if it’s not working, then it looks like you would have to call the gas company.

No voltage to the gas valve, dirt blockage in the valve, and low manifold pressure might also be to blame.

Lennox Furnace Igniter Glows but No Flame

All the reasons mentioned above might cause no flame in your Lennox furnace.

Don’t forget to make sure that the unit is receiving proper airflow. If the filters are clogged, for example, the furnace won’t be able to create the right gas-air mixture necessary for the unit’s operation.

Goodman Furnace Igniter Glows but No Gas

  • Make sure that there is a gas supply and that the proper ignition sequence was followed to fire up the furnace
  • Examine the flue pipe system (there might be an obstruction)
  • Check the air intake pipe system (make sure that nothing is blocking the pipes)

What Would Cause a Furnace Not to Ignite?

  • Issues with the gas line (those include leaks, faulty gas valves, blocked gas lines, etc.)
  • A faulty or improperly set thermostat – make sure that the device is set to ‘heat’
  • A dirty air filter – the burner won’t be able to ignite without proper airflow
  • A malfunctioning pilot light or ignitor – a pilot light that fails to stay lit or a dirty ignitor can prevent the furnace from igniting
  • A broken flame sensor – you might have to replace the element
  • Dirty gas burners – burners that are covered in dirt won’t be receiving the oxygen necessary for the ignition

Read: How To Choose Furnace Filter?

Can Hear Your Furnace Click on but It Does Not Fire Up?

The furnace’s spark ignitor is trying to ignite the burners or the pilot light but is failing to do so. This means that there is an ignition system malfunction.

A dirty or malfunctioning flame sensor, a pilot flame that is not hitting the thermocouple properly, or a gas valve that is not energized might also be causing the problem.

Why Would the Pilot Be Lit on My Furnace but No Heat Coming Out?

  • Wrong thermostat settings
  • Something is blocking the airflow
  • An issue with the fuel supply or the ignition system

Do Furnace Ignitors Go Bad?

Ignitors are the elements in your heating system that have to deal with extremely hot temperatures. No wonder these components can go bad from time to time.

The average lifespan of a furnace ignitor is, in general, 7 years.

What Does a Bad Furnace Igniter Look Like?

The ignitor is located behind the burner panel. It is a small device located near the gas input.

Usually, the element consists of a white ceramic base and a flat metal component. Spark ignitors can have two metal prongs.

If you have noticed that any part of the ignitor has developed a crack or the actual element looks worn out, then it might have gone bad and you would have to replace the ignitor.

Read: Why Furnace Not Responding To Thermostat?

How Do I Know If My Furnace Spark Ignitor Is Bad?

An ignitor that had gone bad will cause all sorts of problems in your heating system.

  • There is cold air blowing from your vents
  • The furnace won’t turn on
  • The furnace comes on, but suddenly stops blowing air
  • The unit is short-cycling
  • The furnace tripped the breaker more than once
  • You can hear the furnace click, but nothing happens after that

How Do You Troubleshoot a Furnace Ignitor?

Check these things before calling an HVAC professional:

  1. Make sure that the furnace’s breaker is in the ‘on’ position.
  2. Every furnace has an on/off switch, ensure that the unit is switched to ‘on’.
  3. If you can safely do that, check the exhaust vent (it should not be blocked by any debris or snow, for example).
  4. Set the thermostat above your home’s temperature.
  5. Make sure that your inducer motor starts (you should hear it).
  6. If the inducer starts and the furnace fires up, then there is no issue with the igniter.

Read: Why Furnace Stops Working At Night?

How Do You Test an Ignitor?

There is a relatively simple test that you can conduct to find out whether it’s your ignitor that is causing the issue. Before getting started, however, make sure to unplug the furnace from the wall, turn the gas valve off, and give the unit enough time to cool down.

How to Clean Furnace Ignitor?

One of the reasons for no flame might be the fact that the furnace ignitor is dirty. This, in its turn, will prevent the element from getting hot enough.

Fortunately, it is quite easy to clean the component.

You can try using compressed air to clean the ignitor or physically removing the element from the furnace and gently rubbing the probe with an emery cloth.

How Do I Clean My Furnace Ignitor Sensor?

Remove a screw to make the flame sensor slide out of its compartment. After that, carefully clean the element.

Can I Manually Ignite My Furnace?

If your furnace has an electronic ignitor, you can’t light the unit manually. In such a case, you can get the heating system working by simply resetting it.

How Do You Trick a Flame Sensor?

You should not trick or bypass your flame sensor as this will not solve the root cause of the problem that you’re experiencing with your furnace. 

Moreover, it is extremely dangerous as the flame sensor is responsible for cutting off the gas to the unit, in case there is no flame. 

Some homeowners choose to bend the flame sensor closer to the actual flame, and this might make your furnace work. But it is not recommended to do that.