No power to ac thermostat

Licreek wrote:
I have a 99 Damon Ultrasport. About a month ago I had to have the electrical control unit replaced. Everything has been working fine. Today I went out and fired up the gene and turned on the ac thermostat and nothing came on. I pulled the thermostat and found I have no 12v power at the connector on the thermostat. I checked all the fuses on the house fuse panel and all are good. So can anyone tell me where the wiring for the thermostat gets power?? I'm wondering if something happened when controller was replaced or is there a fuse hiding somewhere?? All I know for sure is there is no power where the thermostat wiring comes out of the wall... HELP!! Thanks, Lee

whats the "electrical control unit" please explain

I'm sorry I mention to say the controller. My understanding is some units have controllers with inverters and some don't. Mine just has 12v and 120v no inverter

Not sure of your exact setup, but I have read multiple reports of the RJ45 (I think that's the number, may be an RJ9 or RJ11) connector going bad on either the thermostat end or the A/C end. If you have the flat cable like a telephone cable, that could be your problem.

Normally power for the thermostat comes from the furnace which is only powered by 12VDC as compared to the A/C's are 120VAC primary power but controlled via the thermostat and 12VDC.

Are other DC power appliances working? Fridge, ceiling lights, water pump, water heater?

I think you might be confusing 'controller' with 'converter'. The converter takes 120VAC and makes 12VDC to power the coach and keep the batteries charged. If it was recently replaced you could have a problem associated with it and maybe dead batteries. Not unusual to blow the fuses or pop the circuit breakers on a converter when connecting to the coach DC power lines. It will look like its work but it's not.

Thanks for the info. Everything else is working fine both on 12v side and 120v. House batteries are charging gen working. The controller was replaced about 2 weeks ago. Up until yesterday the ac was coming on when I turned it on at the thermostat but yesterday out of the blue I have no 12v power at my thermostat to power anything? Did you say that 12v red power wire at the thermostat gets its power out at the wiring on the furnace?

I haven't a clue where the 12 volt power source comes from .. but in my rig I replaced the thermostat with one that runs off batteries. They don't cost very much, digital, and there are lots of YouTubes on how to install. I replace the batteries about once a year. Another alternative to consider.

ksg5000 wrote:
I haven't a clue where the 12 volt power source comes from .. but in my rig I replaced the thermostat with one that runs off batteries. They don't cost very much, digital, and there are lots of YouTubes on how to install. I replace the batteries about once a year. Another alternative to consider.

the led displays are what use the battery power your unit still needs a 12V source to operate the control boards

Thanks all for input and special thanks to David,traveling. Problem was poor connection at the main switch on the furnace. Fixed connector and MAGIC!! Power at thermostat control again. Thanks again