Heating, Air Conditioning, Fridge, HVAC/HEIL Furnace Won't Light


I have an old Heil gas furnace, model NUGE100AG02.  The pilot light will come on with a strong blue flame, and then shuts off.  My research shows that it may be the ignitor/flame sensor.  I cleaned the sensor as instructed and the furnace light off for about a minute, then shut down. Now it's back to cycling the pilot on and off again.
I also removed the air filter to eliminate that as a possible cause, but that didn't help.
Is there anything else I should check?  Are there schematics or manuals online somewhere?  The ones on the Heil website don't appear to be for this model.

Thank you

Hi Bill, First thing to check is the pilot must be engulfing the thermocouple. Do the main burner's ignite? I would go ahead and replace the thermocouple. Make sure the fitting is tight where the thermocouple attach's to the gas vale.

Let me know what happens.

Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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