How to Fix a Broken Gas Furnace Ignitor

  • 1-3 hours
  • Intermediate
  • 0-80
What You'll Need
Wire brush

Most furnaces fail to operate when the gas furnace ignitor is broken. A gas furnace ignitor is what lights the gas, which is necessary for heat supply. Most furnaces installed in buildings have a flame sensor and an ignitor. If the ignitor fails, the flame sensor will not work. Consequently, the gas supply will be automatically cut off, and the furnace will be shut down. Problems with a gas furnace ignitor can be fixed using simple techniques. However, if the ignitor does not work at all, it will have to be replaced. Here’s how you can repair your broken gas furnace ignitor.

Step 1 – Inspect the Pilot Light

Turn the power off on the furnace. Check the pilot light, and see if it lights properly. The light may go out repeatedly or may not work at all. This indicates a problem with the thermocouple. If the pilot light is working normally, but the furnace is noisy, the furnace may need minor repairs. Also check the air filter; if it is dirty, clean it. Clean the blower blades and lubricate the motor. Finally, inspect the belt attached to the motor.

Step 2 – Inspect the Electrical Service Panel

The next step is to check the electrical service panel and see if there is a tripped breaker or a fuse that is burnt out. Relight the pilot heat and check the temperatures. If the heat is not enough, adjust the air shutter of the burner. Clean the ports of the burner. Check the temperatures again and see if the pilot light remains lit. If not, use a toothpick to clean the pilot orifice.

Step 3 – Inspect the Thermocouple

After you have cleaned the pilot orifice, check the thermocouple for any visible damage. If the thermocouple is not working properly, you may need to replace it. Adjust the pilot once again and set it at a higher setting.

Step 4 – Lighting the Pilot

Check the control knob and set it on pilot. Hold a match under the gas port of the pilot. Press the control knob and see if the pilot lights are on. Hold the knob down until the flame begins to burn brightly. Slowly release the pressure and turn to the on position.

Step 5 – Replacing the Ignitor

If none of these techniques works, you will have to replace the ignitor. Turn the furnace off and open the access door. Disconnect the wiring harness by pressing on the tabs that hold the wiring. Using a screwdriver, remove the hex screws that hold the ignitor to the furnace. If the ignitor is broken or badly discolored, it will have to be replaced. Insert the new ignitor into the furnace, with its tip inside. Using the retaining screws, fasten the ignitor to the furnace. Reconnect the wiring harness and close the access door to the furnace. Turn the power of the furnace back on. Ignite the burner to check whether the new ignitor is working.