[Richard]

Wow, this is a brain tease. I have no clue.

Here are some things to think about. The 120V compressor is powered off the circuit that goes through the inverter. The 120V breaker for that circuit should be in the driver side bay that contains the inverter. There will be other 120V items on that circuit that should be identified on that sub panel box. Do those other items cease to function when the 12V switch is off? If so that would point upstream to some connection between 12V switch and inverter.

The 120V compressor has a second possible intertwinment with the 12V system. When the HWH leveling system is in Autolevel mode. The HWH system will send a 12V signal to a separate wiring junction box close by the 120V pump that bypasses the well pump switch. The purpose is to get full pressure from the pump while trying to raise the coach.

I don’t have any theories.

Thanks for answering the detail questions.
Are house batteries physically disconnected with manual disconnect in battery bay?
Is the coach plugged in to 20, 30, 50 amp?
What brand of inverter, and is it on?


You said you had not noticed this before, is there anything at all about the storage situation that has changed?

This is a GOOD one.