3+ year old 15K rooftop Dometic A/C not working. fan not locked up, capacitor cases not swelled. When it was running, when compressor cut on, fan stopped, compressor continued to run. I shut it off. When I switched to high fan speed from low, breaker tripped immediately. Any ideas?

change compressor run capacitor.

sounds like relay module problem

install hard start kit or defective compressor.

Sounds to me that the compressor start capacitor is the first thing I would check. You will need to get on the top of your camper and remove the outer cover. The capacitor is the part that stores up enough energy to kick start the compressor when it starts. Sometimes a capacitor will swell if bad, but not always. Mark your wiring before removal and have someone test the capacitor to see if it needs replaced. I will be here should you have any questions. If helpful please rate this solution, Thanks Sea Breeze

Here is a link to Dometic Service Manuals Click=> HERE

comparison_good_and_bad_round_capacitors

Hope the compressor getting high amphs due to capacitor weak or loose wiring.Check and replace the capacitor. If still your compressor cuts off, the problem is with your compressor. Thanks.

Bad fan motor or start/run capacitor! The unit overheats and shuts down to protect when high limit is reached

You could start by checking the capacitor. Then use an ohmmeter and check the fan windings. Hook one meter lead to com lead. Then hook the other meter lead to the run lead and then the start lead, reading the resistance each time. Then read from each to ground (compressor case). You could also use an ammeter to check the current draw when it starts. Hopefully it's just the capacitor.

your compressor is locked up. i would try replacing the round start capacitor. you need to check what the exact rating for yours is but I believe one of these two will work for ya. In the meantime do not continue to try to run it, it will kill the compressor.
seth

53-64 mfd

45-53 mfd

Check at the compressor terminals between the Red and the terminal for the overload protector to see if you are getting power to the compressor on startup.

fan motor or capacitor.could be a control issue.better call a pro.