Originally Posted by tbettes
I have a 1960
Overlander with a fairly new dometic AC (4 years lightly used). We have not traveled in the Overlander for about 2 years and the AC has not been on since last summer or fall. I tried turning it on yesterday for a trip this weekend and the thermostat stayed blank. No power? There is power to the breaker that the AC is on and the breaker appears to work (I did not pull the cover and check). I checked that no wires were broken or disconnected at both the thermostat and under the cover on the roof. I am not sure if this is something simple or if I need to take it in. Any ideas??
You didn't specify which Dometic control system you have for your A/C unit, but many of Dometic's digital electronic t/stats get their 12VDC power directly from the upper control board that is located under the A/C shroud on the curb side of the unit.
There is a 3 amp fuse located on that board. If your Airstream fuse that supplies power to the A/C is good, then I would look at the 3 amp fuse on the control board.
The other weak spot in Dometic's power delivery system is the cheap plastic RJ-11 unions that they use to connect the phone type data cable that runs from the back of the t/stat directly to the board.
The upper unit will have 2 black phone-type data cables hanging below the return air opening in the ceiling. Each will have a plastic RJ-11 union on them. You can use either connection point and switching it over might be productive.
Once in that reel, you can also check to see if the control board is receiving 12VDC control voltage by finding the red and black wires coming from the board and checking them with a VOM. you should see 12.0-13.6 VDC on those two wires.