Atwood 38535 thermostat

[Ibrokzit]

I have a Jayco designer 2003. The Atwood 38535 thermostat is obsolete. Has anyone any advice on a substitute thermostat. I do not mind if the furnace only turns into 1 stage.

Also if I just wanted to test the furnace manually ,there are 3 wires to control furnace.
1. a red 20 gauge wire supplying 12 volts
2. a white 20 gauge white wire
3. a white about 16 gauge wire

do I wire all three wires together?

[Old-Biscuit]

Here is the Installation Manual for the Atwood Furnace Model (2 stage 2540) that must use the 2H2C thermostat (3 wires)

See pg 4 for wiring diagram
https://techsupport.pdxrvwholesale.c...ION-MANUAL.pdf

[Ibrokzit]

Thank you Tim for the reply and the manuals.
At the thermostat 38535 there are at 2 bundles of wires.
The one bundle comes from the furnace. This bundle has three wires.
1. A red wire about 20 gauge that is 12 volt+
2. A white wire that is 20 gauge
3. A white wire that is about 16 gauge.
The red 12 volt supplies power to the thermostat.
What is confusing me is the 2 white wires of different size.Usually to run the furnace there is only a red and a white, so would you happen to know what the third wire is for?
Which wire would go together to run the furnace?
The second bundle is from the control unit for the air conditioner.
1.A red for power
2. A yellow for compressor Note: The wire is actually white, but when you trace it back to the a/c control box it goes to the Y terminal and gives the signal for the compressor and the is why I'm calling it yellow
3. A green for fan
4.A blue for your common
Could I make a Coleman Mach thermostat work. It would be OK if it did not act as a two stage furnace
3

[92LandYacht]

From the schematic that was posted, it would seem that you only need to short the two white wires to initiate start. The rest is up to the furnace. the 12V red wire was probably used to power the thermostat.