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Coleman 7900 Series (Presidential III) Model: 7956A856

Posted: Thu May 08, 2008 9:48 pm
by Geminate
Hi,

I am trying to help my Father fix his furnace. He had a service out, and they replaced the blower, but that did nothing to fix the problem.

Coleman 7900 Series (Presidential III) Model: 7956A856
Standing Pilot Furnace Model
Propane

This is the problem as he explains it:

"The furnace was going full blast, even though I had the thermometer turned to its lowest level. The room temp was a little below 40 degrees, so that’s what must have set it off, wasting a lot of propane, since the furnace was back to the previous routine of turning on and off every 30 seconds or so--no way of heating up the house in any detectable degree."

"Last winter, when I turned up the thermostat, the furnace would fire up for several minutes, then the blower would turn on and heat would start coming out of the ducts. But after several minutes, the blower would shut off while the furnace kept going full blast. And after a few minutes, the blower would start up again. So the blower went on and off, on and off, until I would finally punch the System switch off. Adjusting the thermostat had no effect."

Let me know what the problem could be, thanks.
Geminate

RE: Coleman 7900 Series (Presidential III) Model: 7956A856

Posted: Thu May 08, 2008 10:20 pm
by Robert
Hi,

The most common cause for that is a faulty/weakened fan switch.


Fan Switch #7975-3281 can be seen and ordered if needed from left side of page here:

http://www.mobilehomerepair.com/ColemanGas.html



I'm not there to test and diagnose, but that is the most common cause for what you described.



Thanks for inquiring,
Robert

Posted: Thu May 08, 2008 11:01 pm
by Geminate
Thanks for your timely reply! I will order him the part and see how things go.

Thank you very much!
Geminate

RE: Coleman 7900 Series (Presidential III) Model: 7956A856

Posted: Fri May 09, 2008 1:15 am
by Robert
You're very welcome and thanks for ordering.


Hope that takes care of it for him.



Take care and best wishes,
Robert

RE: Coleman 7900 Series (Presidential III) Model: 7956A856

Posted: Fri May 16, 2008 9:00 pm
by Geminate
My father is having trouble locating the Fan Switch #7975-3281. I was wondering if you knew where it's location is for this model? It's not in plain view, and he won't order the switch until he knows that he can replace it himself.

Thanks,
Geminate

RE: Coleman 7900 Series (Presidential III) Model: 7956A856

Posted: Fri May 16, 2008 11:08 pm
by Robert
Inside the rectangular metal controls box on the back wall.


Should be the one on the left if they haven't been switched.


Will have a Limit Switch beside it that looks the same or similar.


Very simple DIY replacement.



Thanks,
Robert