3rd a/c is not working

[Jruhbusch]

I have a 16 momentum and the garage a/c unit doesn’t want to turn on (dometic). When I turn the 3rd zone on the controller is saying -95 and it will only allow me to turn the temp down even more. The ambient temp sensor is reading normal. I’m able to turn the blower fan on but the compressor delay icon just stays on. The other 2 a/c units operate normal with no problems. I bought the camper used 4months ago from a private party and never even turned on the 3rd a/c (my bad). Not sure if I’m doing something wrong or if I have a actual problem? Any thoughts? Thanks in advance!

[FT4NOW]

I would swap the thermostat with the one in the bedroom and see if it works. That will help isolate the problem to the unit or the thermostat. Dont use the one from the main area since that one probably has the heat pump.

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[Jruhbusch]

I thought they are all controlled by the bedroom thermostat? Or am I missing something?

[FT4NOW]

I thought they are all controlled by the bedroom thermostat? Or am I missing something?

I have a 2017, I doubt they changed it between yours and mine. Each of my ACs has it's own thermostat, one in bedroom, one in main area, one in garage. Each also has it's own circuit breaker in the breaker box. 12V power must be available for the thermostats, and the main room AC unit usually has the heat pump.

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[Jruhbusch]

I’ll have to go look again, I know the thermostat in the master bed room has controls for all 3 zones and your able to check the temps on all 3 zones from that controller.

[JCR GD]

My 15 is controlled all from 1 thermostat in bedroom. Just sensors in living area and garage.

OP, back to basics... Are you on 50amp service? What is the on-board EMS showing?

[Jruhbusch]

I am actually plugged into a 30 amp service at the moment. So maybe that is it. When I’m testing it out I have the other 2 units off so the management system is only pulling a few amps

[JCR GD]

The EMS may be shedding the #3 AC unit because only on 30 amp. I would think it would allow #3 if others are off but ???

[Jruhbusch]

From everything I read it should be working if the others are off. Since I bought this used I didn’t get a exact run down on all the operations so just want to make sure I wasn’t missing something silly before I possibly have to take it in.

[JCR GD]

It sounds like you are doing things right. Nothing silly comes to mind.

EDIT: Just FYI, my EMS (PCS) on 30amp with no load. Shows all ACs available.