Coleman 7970a856 ac works but heat will not stay on

[richshafer]

Hello, I just recently switched my furnace to heat and when I switched the heat will come on for approximately 2-3 minutes and turns back off. I have tried cleaning the thermocoupler and the pilot. Also tried a new thermostat but to still no luck. Any ideas on what could be causing this? It worked fine last year.

Thanks,
Rich

[Robert]

Hi Rich,

Would need to check voltages first to see if anything is wrong there.

Does the gas valve lose 24vac signal from thermostat ?



Thanks,
Robert

[richshafer]

I dont think so when the thermostat kicks the furnace on the burners all light up and the blower goes but wont stay on. I do not own any meters is there any other way to know if that could be my problem?

[Robert]

Hi,

No, would need meter to check for voltage to see if there is an electrical problem.

Inspect the burner tube and burner orifice for blockages.


Thanks,
Robert