Coleman Thermostat - Mod# 7956A856, SN# 02907146

Questions about repairs and parts for Coleman furnaces, air conditioners and heat pumps for manufactured homes. Click here for Coleman parts.

Moderators: Greg, Mark

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mikeh304
Posts: 2
Joined: Sun Mar 04, 2012 1:20 pm

Sun Mar 04, 2012 2:21 pm

Hi all,

We have of an issue with replacing a thermostat, not anything gone awry though.
We're getting into the job of remodeling our living room (removing carpet, putting up new paneling, trim, etc.), and one of the things that we definitely want to do is replace the thermostat that has been here from the beginning (home was purchased new in September of 1990). We wanted to replace this with a digital thermostat, and thought we had found one after some research and question-asking led us to the answer "you need a heat-only thermostat since you turn your heat/cool off at the furnace." Naturally, that made sense. We found one cheap and picked it up - the Honeywell T8775A Digital Round Non-Programmable Thermostat. This one seemed to fit what we wanted... we didn't want to put a large box on the wall for doing something so simple and changing the temperature up/down.

All was well until we opened the box and took a look at it.

Keep in mind, changing the thermostat was not a job we intended to take on ourselves, we were going to call one of the services we usually use for heat/cooling repair.

So we open the box and discover there is a resistor that would need installed if the furnace system met certain criteria. Our issue is that we haven't a clue, and the manual seems to be misplaced (even though it might not help much anyway).

Basically, if anyone is familiar with the 7956A856 furnace and it's original 1989/90 thermostat could tell us whether or not the one we picked up could be used with this system (or if we need to pick up a different model) and about this resistor and what would need to be done (if anything)... that would be very much appreciated. I'd like to be able to just call the repair service, hand them the thermostat and let them hook it up rather quickly without problems. There have been no modifications to the furnace since it was put in. Luckily, the only problems have been externally with the AC unit.

I'm linking images from Photobucket showing the plate on the furnace with the model/serial, the old thermostat still on the old wall, and photos of the new one and the resistor and criteria. If these do not come through I will find a new way to supply them. They should be readable.

Thank you for any help you can provide.

The furnace plate with info:
Image

The old thermostat:
Image

The digital thermostat:
Image

The resistor and it's criteria:
Image


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Greg
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Posts: 5609
Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY
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Sun Mar 04, 2012 4:10 pm

Hi & welcome. By the process of elimination I doubt you need the resistor. You do not have a cool only system, It's not a Trane, It's not a boiler so you don't have Zone valves, I doubt it has fan timers.

Thermostats are not hard to change,this link may help.http://www.ronhazelton.com/tips/how_to_ ... thermostat

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mikeh304
Posts: 2
Joined: Sun Mar 04, 2012 1:20 pm

Sun Mar 04, 2012 5:05 pm

Greg,

Thank you so much for your reply. I am checking out the link you provided, maybe I can feel comfortable enough to change this myself. From what I know of the Coleman thermostat, it really should just be two wires, I think.

Again, thank you!

Mike

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