How to Troubleshoot a Furnace with a Pilot Light

Published on: November 15, 2018
Match on fire | Troubleshoot Pilot Light for Furnace | AC Southeast®

If your gas furnace uses a pilot light rather than an electric ignition, pay attention. We have great information for you, including troubleshooting tactics and maintenance tips.

Furnace Pilot Light Refresher


In case you’re a new homeowner, let’s review the basics of a furnace pilot light. A thermocouple is a part of a gas furnace. It acts as a sensor to shut off the gas to the burner if the pilot light is too small or out. So, if the pilot light is under producing heat, it shuts off the gas valve. This safety measure prevents gas leaks into your home. Therefore, if the pilot light goes out, the furnace stops producing heat.


So, if you wake up one frosty morning and it’s terribly cold in your home, look at the furnace and see if the pilot light is lit.   

How to Relight the Pilot Light On Your Furnace


If your pilot light is out, you have to relight it. If you are uncomfortable with this, use AC Southeast®’s dealer locator to find a trusted HVAC contractor near you. They deal with these issues all the time.


Many offer 24/7 service, some at no extra charge. They care about your safety as well as your comfort, so go ahead and call.


If you’re comfortable proceeding, use the furnace’s instruction manual or the instructions listed on the unit door for details specific to your furnace. For the purpose of this blog, we’ll proceed assuming you have a continuous pilot light.


After reviewing the specific instructions, turn your thermostat to “heat” and raise it to 80 degrees.


Find the pilot valve on your furnace, then look for the on/off knob. Turn the knob to “off.” Set the reset button or knob from “off” to “pilot.”


Once you find the pilot light near the gas burner tubes, use a lighter or long match to ignite the flame. If you don’t have either, you can use a long piece of uncooked spaghetti in place of a long match.


Hold the lit match up to the pilot and press the button or knob for 30 seconds. If the pilot remains lit, move the button or knob to “on.”  

If Furnace Pilot Light Won’t Light or Stay Lit


If the pilot light is not cooperating, give it a few minutes and try again. This time, hold the button or knob for 60 seconds. This is to make sure the thermocouple has enough time to warm up.


If the light goes out again or won’t stay lit, it’s likely a problem with the thermocouple. This part can be easily replaced. All is not lost!


If the pilot light is lit, but the flame is wavering, it may need to be adjusted. Also, the flame should be blue instead of yellow. If it’s not blue, it’s not the right temperature and miscommunicating with the thermocouple. Your furnace has a screw to adjust the flame on the pilot light. Refer to your specific instruction manual for details.

Find a Local Gas Furnace Expert


Contact AC Southeast® today to find a licensed and reliable HVAC expert in your area. As a homeowner, it’s important to have a home services partner for ongoing heating service. When you need furnace repair or replacement your HVAC partner is there for you!