I have a Weather King furnace and a White-Rodgers thermostat. Occasionally, the burners will cycle and the next time it would work fine. When it does malfunction, the exciter fan starts, about 30 seconds later the burners will ignite, but they go out before the fan motor starts. The burners continue to cycle on and off until the furnace shuts down. The furnace will immediately start up again and go through the same process. This has been going on for a few weeks, but the frequency wasn't enough to affect the temperature in the house. The past couple of days, the temperature on the thermostat would drop about 4 degrees below the selected temperature before the furnace would kick on. Today, it didn't come on and no matter what I do, the burners cycle. PLEASE help me!!

Clean the flame sensor.

Thank you for your help. I was looking for a flame sensor in the burner chamber, but don't see it. Where else should I look? Is it on the electronic ignition portion? What should I use to clean it? Thank you.

I believe if you surf around in the beginning of this board under sticky notes it will show a example of a flame sensor and the location.

Look at the extreme far left or right of the burner box. There will be a probe that the flame should hit within a few seconds.