[B and C]

Went to the coach today and the 120v compressor was not working.  After checking fuses I found when I switched on the 12v master switch on the control panel in the coach where the lights, step, etc. (just inside the coach door) are controlled, the pump started right up and pressured the system up.  Is this normal?  If not, where do I start looking for the problem?  I don't recall having to do this is the past.
Thanks

[encantotom]

my compressor will run when the master 12v switch is off. so not sure why yours is doing that.

tom (i have an 02 as well)

tom

[Richard]

Are you comfortable measuring voltages in live 120 circuits?

If so, I would pull the cover off the Square D well pump switch that controls the pressure of the 120V pump and check incoming power.

Does the pump go off, when you kill the 12V master switch?

Do you have your 12VDC pump turned on? Is it possible that is the pump that came on and pressurized the doors and potties?

[B and C]

Thank you Richard.  The 12v pump is turned off and when I turn off the 12v master switch the 120v compressor shuts down.  If I let it run, with the master switch on, the pressure builds to the cutoff point, ~102 psi, then shuts off n the pressure will drop over about an 1 1/2 hours to ~90 psi, then 120v kicks on and pressures the system up back up to the cutoff pressure.  Pressures are from the gauge off the pressure switch.


Chris

[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.

[Richard]

One more stupid question,

If you access the back panel where the 120V switch for the compressor is located, do you measure 120VAC on that switch, or 12VDC. I could take mine down and measure, but my coach does not act the same as yours so it wouldn’t help.

If it is 12VDC on that switch then somewhere is a 12VDC relay that switches power to the 120VAC pump.

[B and C]

I'm stumped.  It did not do this prior to having the generator pulled for a rebuild.  I tried to measure across the contacts on the pressure switch and got 12v.  Not sure if I measured correctly.  The coach is plugged into 30 amps and the house batteries are on.  I am unsure of the inverter brand.  
Chris

[Richard]

Can you post a pic of where you measured the 12V across the contacts?
Where is your 120V compressor? Is it in the bay with the generator?

[B and C]

The 120v is in the bay with the generator radiator.  

I hope the picture came through...I measured across the two contacts circled in blue.  

Chris 

   

[Richard]

If your measurement was correct, that does not make sense. Because if that is 12VDC, then the 120VAC pump is not going to operate.

Could you check again, please.

And does the voltage go away when the 12V master switch is off.