AC Compressor runs long (after an shutoff).

[tcrespo]

New (to me) RV and I'm definitely a newbie, so please bear with me.

When I turn on the breaker to my front AC unit, immediately (even with the thermostat turned off) I can hear a humming from the unit (which I'm assuming is the compressor). It will stay on for approximately 4 to 5 minutes, regardless of the settings on the thermostat.

If I turn on the thermostat, the AC comes on and is cooling just fine. When it completes the cycle, the fan shuts off but the humming continues, again for roughly 5 minutes.

This process cycles around and around - AC is cooling great, but I think the compressor is having issues.

I don't know the specific Dometic model of the unit, but it has the 3107541.009 control board/unit installed.

Both AC units are the same and the rear one is functioning normally.

Should I swap the control boards between units to see if that narrows things down?

Just looking for some general guidance here - thanks in advance!

Tom

[Grit_dog]

tcrespo wrote:

trailrider wrote:
The relay on the control board that sends power to the compressor is stuck on.

First thing I did this morning - gave the relay on the left a nice tap and the compressor turned off. To be safe I'm going to replace the board.

Thanks again - very much appreciated!

Why not slap a new relay in it. Or verify the relay contacts are sticking (IE when turned off, the signal wire from the board to the relay should be dead and if it is and the comp is still running, then you’ve isolated relay as the issue likely). Sounds very feasible since if the board was still powering the relay and keeping it latched, then a thump wouldn’t have shut it off.

[TurnThePage]

I have 2022 model year Dometic A/C with very similar behavior. Thanks for the tip on the relay.

[tcrespo]

trailrider wrote:
The relay on the control board that sends power to the compressor is stuck on.

First thing I did this morning - gave the relay on the left a nice tap and the compressor turned off. To be safe I'm going to replace the board.

Thanks again - very much appreciated!

[trailrider]

The relay on the control board that sends power to the compressor is stuck on.