Atwood 2540 2 stage furnace thermostat

[Rmgrose]

Background-I have installed several house thermostats in rvs, so when my dads thermostat died I replaced it. The ac works fine and when he used the furnace it did not. He asked the dealer to look at it and they said it is a two stage furnace and has a special thermostat that isn't readily available. We told them to let it go while we researched this issue. I have attached screen shots of Atwood wiring and thermostat and a Honeywell wiring diagram. I need to pull the wires out again to see what color wires was where, but was wondering if anyone else has ran into this. He has an older Jayco Designer series and what I found online is scarce. Thanks

[mini4mw]

Not an HVAC guy, but I have replaced several as well.

Is the fan kicking on and blowing cold air or not doing anything at all?

2 stage is just low heat and high heat (2nd stage). If low heat doesn't warm, 2nd stage kicks in.

2 stage should have 4 wires from furnace, power, fan, heat stage 1 (W1), heat stage 2 (W2). The Atwood diagram only has 3 for some reason. A 2 stage can run with a single W wire if W1 and W2 are jumpered at the control board (or thermostat if two wires come from furnace). Stage 1 kicks in and 2nd stage kicks in 10 min later if it hasn't turned off (warmed up enough). Looks like the thermostat is only 1 stage - only W1 - no W2.

I'd double check the wiring first no matter what it is doing. If the fan is blowing but no heat, I'd focus in on the W1/W2 wiring.

[poohbear]

Just glancing thru Atwood manual I think thier tstat is actually a " communicating " type. I will look when have more time plus I need to get on the big screen to follow schematic.. One wire is a 7.5 volt lead so I'm thinking you are locked in to the Atwood thermostat.

[poohbear]

Forgot to ask, why do you think thermostat was bad ? More likely the control board in furnace.

[Rmgrose]

Thank you for looking. I seen some of the original thermostats online that we might need to buy. The display on his didn’t work so you couldn’t see the temps.