I have a lennox whisper heat furnace model g20q3e-75-2 that won't fire the burners. The piolet goes on the blower goes on and then it all shuts off and I have to kill the power to the furnace to start it up again. After I do this 3-4 times the burner will fire but then I have to di it again when my hoouse gets cold.
Check for stable uninterrupted 24 VAC power to the ignition control. When the igniter is sparking, you should have 24 VAC going to the pilot valve section of the gas valve.
At this point, the ignition control will look for the minimum flame current before it will turn on the main valve. If it is not turning on the main valve, and you have no way to measure flame current, clean the flame sensor with steel wool.
You should not replace the ignition control until you check and make sure it is bad.
Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.
The pilot burner and flame sensor may need cleaning.
I am not an employee of CozyParts. The opinions that I post are my own.
Please have your furnace inspected annually by a qualified service technician. Have all of your fossil fuel appliances tested annually for carbon monoxide production by a professional.
Get a good Carbon Monoxide Alarm. Replace it according to manufacturers recommendations usually every 3-5 years. CO concerns are not just for the winter but 24-7. UL approved alarms alarm high. For a low level alarm do a search for CO Experts or NSI 3000 a low level CO monitor.