Coleman Model 7970C856

[Drahz]

I have a Coleman Model 7970C856, standing pilot style and no a/c, just the furnace. The burner shuts off after like 30 seconds of burning. The pilot and everything shuts down. Usually, the blower will come on right after the burner stops. I read in past posts to check the voltage to the valve to see if it loses power or any fluctuation. There was none. I had 25.1v on the gas valve the whole time, even when it cut off, and also when the blower came on. It stayed a steady voltage. So, I went on the roof to check for any venting restrictions and found nothing. I replaced the high-limit just in case, but it didn't make a difference. There doesn't seem to be any other parts to check! LoL! I could really use some advice. Hope to hear from someone soon!

[Robert]

Hi,

Replace the thermocouple and if it does it still after that, you'll need an hvac tech to test gas valve.


If needed, we have a thermocouple in the coleman gas furnace store page that can be ordered through PayPal.


Take care and best wishes,
Robert

[Drahz]

Thanks for responding. I forgot to mention, the first thing I did was replace the thermocouple. That was my first thought, but it didn't help . Looks like a new gas valve is needed, eh? Besides the valve, could there be any other possibilities? Like I said, there don't seem to be any other parts to even check. It looks like a fairly simple system.

[Robert]

Hi,

On the gas valve, it's cut and dried. IF it has correct input gas pressure and full 24vac to gas valve, it should have correct manifold pressure.


With a new thermocouple, check those pressures or replace on a chance the pressure is good.



Take care and best wishes,
Robert