Need help with Dometic Thermostat/HVAC

[Hjay]

Hello,
New here and rented an RV in Denver to see the western part of our country for my 50th. They gave us a brand new 2022 Thor Quantum 24 KM with little instruction. Due to COVID they sent me a video, gave me a notebook with printed instructions (not about everything) and did a very abbreviated walk through. Needless to say- learning a lot on the fly over the last 2 weeks.
We are having a problem with the thermostat not powering up. It worked the first couple of nights- but since then nothing. We’ve checked breakers and fuses and that does not seem to be it. It’s a Dometic thermostat that is very small. I’ve downloaded the owners manual and everything I see is about a different model thermostat. Anyone have suggestions on what might be causing it?
Thanks!

[16ACE27]

Very little info to go on so I'll make some assumptions:

It's a rental, so you probably have a simple thermostat not the superwhamadyne computerized control system.

Are you plugged in to SP?
What is the status of your battery disconnect?

The thermostat gets its power from the furnace which is 12 VDC from the house DC buss. The furnace and usually the Fridge control power is on a combined circuit with the fuse labeled "Appliances".

Without control power to the thermostat neither the A/C nor the furnace will work.

[Hjay]

So- everything else works when plugged in to shore power or with generator running- including microwave/convection oven (which only works with SP or generator). Nothing on the thermostat when plugged in or when generator is running.
Thankfully we have had beautiful weather and it’s been chilly at night but plenty of warm blankets to keep us comfortable. We turn this rental in on this Friday- so we can deal with it. Was thinking I may just be missing something simple.

[JimOIB]

Ah…you want heat. Is the thermostat in the heat mode and the temperature set so it will heat? And…is the propane valve open. I just have to ask…

Plus, I do believe the thermostat has a couple of AA batteries in it…it may not work if they are drained. Replace them.

[Hjay]

The thermostat does nothing. The display does not light up (it did once- but nothing now). Does not respond when pushing buttons. Attached are photos

[16ACE27]

Originally Posted by Hjay

The thermostat does nothing. The display does not light up (it did once- but nothing now). Does not respond when pushing buttons. Attached are photos

Because it is not getting 12 VDC from the furnace. You "may" be able to open the furnace door from the outside panel and and operate the on/off/reset switch a few times: maybe it's a dirty connection; otherwise it's an issue the rental company will have to resolve. Call them and ask for a mobile tech to come out and fix your problem.

[JimOIB]

I believe this is a “communicating” thermostat since it is 3 wire. It has a separate control box powered by 12v from a dedicated source according to the manual.

https://store-u2qvrsnw19.mybigcommer...-Manual-WM.pdf

I would check the power distribution center to see if it is on a fuse and check the fuse.

Otherwise call the rental company to send a tech as mentioned above.

[16ACE27]

Originally Posted by jimbo12

I believe this is a “communicating” thermostat since it is 3 wire. It has a separate control box powered by 12v from a dedicated source according to the manual.

https://store-u2qvrsnw19.mybigcommer...-Manual-WM.pdf

I would check the power distribution center to see if it is on a fuse and check the fuse.

Otherwise call the rental company to send a tech as mentioned above.

Yep, you're right Jimbo. I had one of those thermostats in my last TT but never had any issues with it so didn't realize it was simply a user interface.

So with only 3 wires going to it; + 12 VDC, - 12 VDC (Ground) and COMM it appears it has lost its dedicated 12 VDC supply from the power center. If it ain't as simple as a blown fuse on the DC power center, then the OP should leave it to the rental company to resolve.