FURNACE NOT LISTED ON THERMOSTAT

The dip switches in the roof units determine what shows up on the thermostat. If you have not made any changes in the roof units then I suspect you are right about a bad control board.

This is for Dometic units. Not ssure of other brands.

If you have Dometic(2002) Tiffin was using Dometic. I have NEVER seen a upper control board be bad and not show a function. Odds are, the upper control board Furnace DIP switch needs to be turned Off then ON, to verify communication. IF you have had a repair on the front AC recently, then the Installer may not have turned the Furnace DIP switch ON. Doug

Hi Doug. Where would that upper control board dip switch be? Happy Thanksgiving!

Hi Doug. Where would that upper control board dip switch be? Happy Thanksgiving!

https://pantherrvproducts.com/dometic-duo-therm-3311557-000-4-to-5-button-comfort-control-center-board-only/?gclid=EAIaIQobChMI69aOs-qN5gIVSb7ACh1lyQRREAQYASABEgIO0fD_BwE

The red block with the 8 whites switched is it. Pin number 4 is the furnace. Doug

My TT air conditioner died before I ever took the trailer out for the first time. Dometic had a bad run and I got lucky. When the dealer replaced it under warranty, I brought it home and did my usual OCD double checking. I saw that the furnace was no longer listed in the thermostat. I took it back to the dealer and the service guy spent 2 hours trying to figure it out. Then he called the service manager over. As soon as he explained what was happening, the service manager told him the dip switches inside the roof unit were set wrong. Took 5 minutes more to fix, and most of that was getting the ladder.

I can see how that could be it but nothing has been changed. This happened all of a sudden. I have a new furnace board coming in tomorrow so hoping that'll do it.

NoSnowInAZ wrote:
I can see how that could be it but nothing has been changed. This happened all of a sudden. I have a new furnace board coming in tomorrow so hoping that'll do it.

If you are saying you have a FURNACE board coming and NOT an AC board, you just wasted your money. WHY do people come to these forums for help(they obviously know nothing), get advice and then do what they want anyway?????????????????????????????????????????? Doug

Doug, SIR -I had no service work done on the AC unit - no dip switches had been changed by either me or any tech.
Must be an incredible feeling to be so GD perfect. Find another forum to "help out" with your valuable assistance.

NoSnowInAZ wrote:
Doug, SIR -I had no service work done on the AC unit - no dip switches had been changed by either me or any tech.
Must be an incredible feeling to be so GD perfect. Find another forum to "help out" with your valuable assistance.

Actually, Doug is a professional RV tech. He does this stuff for a living as his day job.