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Bill
Bill, HVAC Technician
Category: HVAC
Satisfied Customers: 318
Experience:  15+ years service tech.
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I have a Lennox G40UH(X) series furnace with a pilot light

Customer Question

I have a Lennox G40UH(X) series furnace with a pilot light that won't stay on. It keeps blowing cold air into the house. What can I do?
Submitted: 7 years ago.
Category: HVAC
Expert:  Bill replied 7 years ago.

hello, i didnt think this model had a pilot, it should has a hsi ignitor looks like this and is in front of one of the burners. can you see any

flashing lights thru the viewing hole in the lower furnace panel?graphic

Customer: replied 7 years ago.
Yes there are flashing lights
Expert:  Bill replied 7 years ago.
ok watch the flashing it will tell us a trouble code. example : first light two flashes second light two flashes= code 22
Customer: replied 7 years ago.
the two lights are blinking back and forth
Customer: replied 7 years ago.
The system says low flame signal... check flame sensor then flips back to normal operation then flips back to the other one.
Expert:  Bill replied 7 years ago.
if you can follow the ignitor wire back to its connection at the control board, try to unplug it than plug it back in ,may have poor connection.
Expert:  Bill replied 7 years ago.
also try to locate the sensor and do the same and try to clean it with steelwool/fine sand paper/scotchbright pad.graphic
Expert:  Bill replied 7 years ago.
did this get it going?