Coleman T-Stat Issues

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

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777stickman
Posts: 4
Joined: Thu Feb 07, 2013 7:14 pm

Fri Feb 08, 2013 4:26 pm

Coleman gas furnace model DGAA077BDTA with Deluxe Blend Air II (7681-8171/B). Home manufacture date 2004. T-Stat 7900/7541/A four wire. House will come up to set temp and furnace will shut down only to start up again a minute later for 3-5 mins. This cycle will continue for 4-5 times before it finally satisfies itself. I've adjusted the anticipator for shorter and longer times with no help. Is there a digital set back type t-stat available for this system?

Thanks.........Steve


DaleM
Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Sat Feb 09, 2013 7:05 pm

Disconnect the Blend Air system at the furnace, leaving all the other low voltage (thermostat) wiring the same. On these secondary cycles, is the burner going or just the blower?

777stickman
Posts: 4
Joined: Thu Feb 07, 2013 7:14 pm

Sat Feb 09, 2013 7:24 pm

Disconnected the small Red, Wht, Blk & Grn connector from the Blend Air box? Attic fan came on. Yes, the burner operates on each of the secondary cycles.

DaleM
Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Sun Feb 10, 2013 3:12 pm

Here is what I would try. Get a cheapy heat only thermostat and about 25' of 2 conductor thermostat wire. Disconnect your current thermostat, wire the heat only thermostat into the system but using only the red and white wires of the low voltage circuitry in the furnace ( the heat wiring only). Hang this thermostat anywhere, I usually just drape the wiring down the hallway and hang the thermostat over a door. Try that for a few days to see if your furnace operates more regularly. This will eliminate your thermostat, it's wiring and the low voltage wiring going to the condensor unit. Basically a cheap way to troubleshoot the furnace seperate from the low voltage field wiring and tstat. Also look at that Blend Air. Nothing should operate once it's low voltage wiring is removed. This little test will eliminate that system as well.

777stickman
Posts: 4
Joined: Thu Feb 07, 2013 7:14 pm

Sun Feb 10, 2013 6:45 pm

Thanks Dale: I'll try that. The one question is, which wires to remove from the Blend Air? I'm now thinking you mean the larger wires going into the control box. When I removed the plug at the bottom it just turned on the attic fan, which is supposed to be normal from what I've read on the site. Thanks again and I'll post back............Steve


DaleM
Posts: 385
Joined: Wed Apr 07, 2010 10:07 am

Mon Feb 11, 2013 3:11 pm

Steve, there is a red, white, green and (I think) yellow wire tied into the thermostat wiring from the Blend Air box. Those are the wires you need to dosconnect. Those are usually larger wires than those coming from the tstat to the furnace.

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