Thermostat issues

[MaineCamper11]

I have a 2021 26DBH and my heat/ac thermostat is dead. About 2 weeks ago, I spoke to the dealer and they said that it was probably due to plugging in somewhere with low amperage which fried the thermostat. So I replaced it and everything worked. 2 weeks later, the screen is blank again and none of the heat or ac can be turned on. I’m kind of doubting the low amp theory. It’s getting about 12.9v on the voltmeter.

Anyone have any ideas on where to go from here? I don’t want to buy another thermostat to just fry it again.

[TowPro]

I don't know anything about your system, but just for the heck of it check out what I found.

Coming from the thermostat was solid conductor wire, maybe 22g with I think 2 wires going to heater and 2 going up to AC. On mine the AC supplied 12V to the thermostat to run it. This 22g wire goes up to the ceiling (had to remove the AC ceiling grill to see this) and this solid conductor wire is crimped to about a 14 or 16g stranded wire in the AC ceiling assembly using a crimp butt splice. This is a recipe for disaster. I was able to just lightly tug on the solid wire and it pulled out of the butt splice. I was on the road when I finally found this problem, so I just used a wire nut thinking I would solder it later. Wire nut fixed the problem so I never did go back and solder it.

[MaineCamper11]

Thanks for the response. I was able to figure out it was a bad ground. I can ground the 12v thermostat to the 110v outlet next to it and it actually works. But I can’t get the thermostat to ground through the 12v system. .