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Weird Furnace Problem [message #370835] Fri, 16 December 2022 16:00 Go to next message
Carl S. is currently offline  Carl S.   United States
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
Senior Member

I have a Sol-Aire furnace in my coach that has been checked for Co emissions and found to be operating properly. It has recently been operating in a way that points to a bad flame sensor, ie it turns on with the thermostat, runs for 30 seconds or so, then shuts off. If I push the re-set button, it will fire back up (with a nice blue flame) and if I hold the re-set button for 30-45 seconds, it will stay running.

I removed the flame sensor (it was loose) and cleaned it, but when I re-installed it, the furnace started running, without any gas to it, and wouldn't shut off. Turning on the thermostat causes the burner to fire, and it puts out plenty of heat, but when I turn off the thermostat, the blower keeps on running indefinitely, although the flame shuts off. Nothing I can find points to this as a symptom of a bad flame sensor.

Any ideas? I'm thinking the flame sensor is bad and is causing a constant connection to the fan, or it is a control board issue. Any help would be appreciated.

Thanks.


Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
Re: Weird Furnace Problem [message #370836 is a reply to message #370835] Fri, 16 December 2022 18:13 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
30 seconds seems long to have gas valve open if no flame sensed after ignition period.
I’d think the “no flame” being sensed should shut the valve. I think closed stat contacts will still run the fan, as the fan is also the draft inducer on the other side of the motor. Can you check if you knocked or shorted something in the process?
I have a Suburban so can’t comment further. The manual should be posted here in Billy’s files.


John Lebetski
Woodstock, IL
77 Eleganza II

[Updated on: Fri, 16 December 2022 18:15]

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Re: Weird Furnace Problem [message #370838 is a reply to message #370836] Fri, 16 December 2022 19:31 Go to previous message
Carl S. is currently offline  Carl S.   United States
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
Senior Member

It may be less than 30 seconds, maybe more like 15. I'll get a new flame sensor and see if that helps, meanwhile, I'll double check to see if I crossed up some of the wiring somehow.

Thanks.


Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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