Ducted AC is "humming" when thermostat trying to turn off

[RawFaith]

Well,
It all started when we evacuated from Irma. Being fulltimers not much "storm experience" decided that perhaps it isn't very wise to try to figure out how much wind it takes to flip a 5er, so we cowardly ran.
Anyways, at the SC campground apparently something was going on on their electrical grip. First only one of the "hot legs" was providing power, so we had power on 1/2 of the trailer. After flipping brakers at the pedestal ( RV UNPLUGGED ) we finally got the full 50 AMP at steady 120V on each leg.
Power went out during the day, and after that we are experiencing the AC issue : Once the rv reaches the thermostat set temp and the AC supposed to turn off, a constant humming noise comes from the heat pump until flipping the braker off.
Turning the heat pump ON in AC mode blows hot air for a while until you hear as if the compressor will turn on and the cold air starts to blow.
could this be a thermostat issue or could be some electronics at the heat pump.
Dometic 15K BTU heat pump.
Thank you in advance for your time

 

[hoefler]

Check your incoming power! Since the CG is having electrical issues, you may have/or not damaged some of the componants that run on 120 volts. I would find another park ASAP.

 

[RawFaith]

We actually stayed only for a day in that campground. and after that is when the problems started. No other issues. Just the fact that the AC "hmmmm" noise when trying to turn off.Before spending $100 in a thermostat that may not be the issue, any ideas about how to troubleshoot this?

 

[danemayer]

There's probably a control box somewhere near the air conditioner. Because the thermostat (at least one in the rig) controls both A/C and furnace, it does so by sending signals to a control box that powers the furnace and signals the A/C unit. If you have to shut off the circuit breaker to turn off the A/C unit, the control box might have a relay or other component that's stuck.

It's also possible that the electrical problems you experience might have damaged a control board on the A/C unit, or in the control box.

 

[RawFaith]

There's probably a control box somewhere near the air conditioner. Because the thermostat (at least one in the rig) controls both A/C and furnace, it does so by sending signals to a control box that powers the furnace and signals the A/C unit. If you have to shut off the circuit breaker to turn off the A/C unit, the control box might have a relay or other component that's stuck.

It's also possible that the electrical problems you experience might have damaged a control board on the A/C unit, or in the control box.

Never used the furnace and I was under the impression that the furnace has its own thermostat that is next to the Ac one. Where could I look for that control box?
When I opened the AC to do the vent mod for better airflow i found all kind of weird wire and plugs ( like phone lan lines) and the usual box with 120v.
I guess I need to find that control box to test the thermostat?

 

[danemayer]

Never used the furnace and I was under the impression that the furnace has its own thermostat that is next to the Ac one. Where could I look for that control box?
When I opened the AC to do the vent mod for better airflow i found all kind of weird wire and plugs ( like phone lan lines) and the usual box with 120v.
I guess I need to find that control box to test the thermostat?

On our 2011 LM, the thermostat for the living room A/C also controls the furnace. The gray box with multiple connectors, above the living room A/C air return, is the control box.

 

[cookie]

Never used the furnace and I was under the impression that the furnace has its own thermostat that is next to the Ac one.

This caught my eye. I think you might be confusing the thermostat for the heat/cool with a thermostat for a fantastic fan.
The thermostat for the heat/cool will have a switch to toggle between heat and cool.
The other thermostat will be for the vent fan in the kitchen. To turn the fan on, turn that temperature adjust lever up just a bit and the fan cover should open and the fan turn on.

Peace
Dave

 

[RawFaith]

This caught my eye. I think you might be confusing the thermostat for the heat/cool with a thermostat for a fantastic fan.
The thermostat for the heat/cool will have a switch to toggle between heat and cool.
The other thermostat will be for the vent fan in the kitchen. To turn the fan on, turn that temperature adjust lever up just a bit and the fan cover should open and the fan turn on.

Peace
Dave

Thanks Dave,
Here are some pics of what we have.
The FF is in the Kitchen Island and the other 2 are on the wall by the pantry. My apologies if I'm totally confused, but since I'm battling a bad cold...I'm literately brainless..