Gas Furnace Repair

man working on a gas furnace
  • 2-4 hours
  • Advanced
  • 150-300
What You'll Need
Long matches
Two open-ended wrenches
Pilot jet cleaning tool
New furnace thermocouple
All-purpose oil

Anyone who has owned a home in a cold climate knows that gas furnace repair is virtually inevitable. Even if you have very little or no experience repairing a gas furnace, if you have intermediate handyman skills and the right tools and instructions you should be able to repair a gas furnace without major problems. Here are five tips you can use to repair your home furnace:

Tip 1 - Re-light the Pilot Light

If your pilot light has gone out, gas will not feed into the burner, even though all other systems in the furnace are functioning properly. If so, all you will need to do is re-light it. First, find the gas cock and turn it to the "Off" position. Then, while you are turning it to the "Pilot" position, depress the Pilot Reset Button. Finally, hold a lighted match near the pilot. If the pilot light is functioning normally, it will then re-light, allowing you to return the gas cock to its "On" position.

Tip 2 - Clean Pilot Light

If after attempting to re-light the pilot light it still does not come on or will not stay on, it may be because it is clogged with dirt, requiring you to clean it. First, shut off electrical power and gas to the furnace. After waiting 30 minutes for any unburned gas to clear away, use 2 open-ended wrenches to remove the gas tube and thermocouple from the control housing, then, disconnect them from the pilot housing. Using a pilot light jet tool, carefully clean the pilot's jet.

Tip 3 - Replace the Thermocouple

Before reattaching the pilot jet gas tube, install a new thermocouple to replace the old one. Then, reconnect gas tube and thermocouple to the control housing. Now restore electrical power and gas flow to the furnace and try lighting the pilot again.

Tip 4 - Adjust the Burner

Color of the burner flame will be a good indication whether or not the mixture of air and gas is at the right level. If this mixture is right, the flame should be yellow at its tip and blue-green at its center. If your burner flame is a different color than this, you will need to adjust its mixture level. First, loosen the locking screw of the air shutter. Adjust the shutter by opening and then closing it and observing the flame color as you do. You'll notice a change of color in the flame. When the flame color is right, tighten the screw to lock the shutter.

Tip 5 - Oil Squeaky Furnace Blower

A furnace, whose blower squeaks or vibrates when it turns, may need only to be oiled. Turn off electrical power, and then remove the access panel cover. Locate oil ports and apply a few drops of oil into each one. Next, align blower pulleys. Loosen the mounting bolts and align the pulleys by adjusting the position of the motor. Finally, tighten the bolts, and restore electric power.