Furnace not working

[JackMS]

My furnace will not come on at all. It is an Atwood 8535IVDCLP. I found the procedure to bypass the thermostat and it works when I do that. So I was about to order a new thermostat but I got thinking.

The thermostat is a dometic 5 button. I replaced the front a/c heat pump about 3 years ago and I had to order an additional circuit board to swap out on the unit to make it work with my thermostat. Both a/c's are dometic penguins. I think I used the furnace since then but am not absolutely positive of that. Is there anything on the roof a/c I should check first or is it most likely the thermostat? If the thermostat is the issue, would I be better ordering the updated thermostat and putting the original board back in the front a/c? Or is it even possible since the rear a/c is the original 2005 model?

I know a lot of questions but I know there are a lot of very experienced a/c guys here. Thanks in advance.

[MountainAir05]

http://bryantrv.com/docs2/docs/ccc5.pdf

http://bryantrv.com/docs2/docs/acservice.pdf

There is a wire from the front AC down to the heater.
Also do a reset on the thermostat and see if your heater shows back up before you start tearing into things. You should print these out if you do not have them.

If the AC are working then thermostat should be working but ensure you have the heater selected after you do the reset.