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Bob86ZZ4 · 05-07-2010, 07:53 AM

I bought my rig used last summer. Didn't use the Coleman Mach roof airs too much. It's been cool this spring and I'm hooked to shore power. Last night I figured I'd use the heat setting rather than turn on the gas furnace and heat the whole rig since I could just shut the bedroom door and stay warm with that. My thermostat is white and on the left side there is a slider switch that I slide down to the bottom "heat" position. I set the temp on the right and it started heating up. When it reached the proper temp it shut off. When it got cooler it would turn back on. All is good. Except turning on and off is annoying. I tried setting the fan switch over on the right of the wall control to "on low" or "on high" and it doesn't turn the fan on. The fan only runs when it's calling for heat. Is my wall control wired up wrong? Shouldn't I be able to run the fan constantly? If I turn the left switch to "off" I can then turn the fan on with the right switch but it doesn't matter "low" or "high" setting, it's either off or on. Anybody know if I can run the fan all the time on and have it cycle for the heat? Maybe the thermostat wasn't wired up properly? I'll try to post a picture of the thermostat so you know what I've got but I'm not too good with the technical stuff.

Bob86ZZ4 · 05-07-2010, 11:44 AM

Actually, now that I've thought about it some more, I don't think that fan speed switch does anything. I think the left slider is the only way I get the fan to run continuous by setting it to the "fan" position. I'm going to have to take it apart and see if there's anything wired to the fan speed switch. Anybody able to run their unit in "heat" mode and keep the fan on continous?

Bob86ZZ4 · 05-11-2010, 09:14 AM

The thermostat has 6 wires connected to it. Yellow, white, blue, green, red, and gray. It looks like that's all they use, I can't find any unused connections on the circuit board. So, I'm confused as to why the fan speed switch has no effect. Does anybody else have this thermostat and can set the speed switch to one of the "on" settings and have their fan come on? I wonder if there is something wired wrong (on not wired at all) in the roof units? I guess before taking one apart I would like to see if somebody else can set theirs to "heat" and then set the fan speed switch to one of the "on" settings and their fan will run continuously.

Gary RVRoamer · 05-13-2010, 11:19 AM

I can, but I have a different t-stat than you do (Atwood Comfort Control System). When I select heat, I get heat pump as long as it is effective and then it turns onthe gas furnace to assist.

Is your a/c a heat pump or does it have electric heat strips? Might make a difference in how the fans works.

Bob86ZZ4 · 05-13-2010, 08:13 PM

Thanks Gary, my gas furnace is a totally seperate system and has a seperate thermostat for that. The Coleman roof units (one in the bedroom and one in the living room) each have one of those Coleman thermostats. And I think they're called heat strips or something, they only work by electricity. So I guess it's a bit different than what you've got. Darn. I'm hoping I can find somebody with an identical roof unit and wall thermostat and see if they can run the fan continous when in heat setting. I just can't figure out why they have a fan speed switch that does nothing.