[HoosierDaddy]

My microphor has never worked on the 12V air compressor alone. Today I was trying to sequence the events to determine what to repair. So I turned on 12V comp. and let it run til it shut off. ( probably 7-10 minutes). I flush the toilet and it "stalls out" after the flap in the bowl has closed. It sits there leaking air and gurgling as the 12V comp. runs, eventually the bowl flap appears to leak as the air pressure is lost. Air pressure at the regulator is 5-6#.  If I go to the air pressure regulator and shut the air off to the toilet the compressor eventually tops off the tank and shuts off. Then if I open the air pressure regulator, as the air pressure reaches around 25# I can hear air hissing in the system and then as the pressure builds to 38-39# I hear a small thump in the toilet and everything seals up normally. I have tried this procedure with a starting air pressure of 40# as well as 45#.
I rebuilt the toilet last summer and overall performance improved. It works fine using the engine or 120V air comp. It acts as though there is not enough air volume/pressure to complete a flush even though the 12V compressor kicks on almost immediately.

[Richard]

Try increasing the air pressure out of the 12v to around 55 to 60 psi and see what happens. You may have to adjust the well pump switch on the 12v pump.

I am assuming the potty works fine on 120v aux compressor and also with the big compressor on the engine?

[HoosierDaddy]

Yes potty works fine on engine or 120V. I tried increasing pressure today but 12V tops out at 45 psi. I will have to adjust switch. The same air regulator regulated the other two air sources as well. Should I be concerned about running potty at 60 psi while on the other air supply?

[bikestuff]

Here is what happened on mine.....

On my coach, I adjusted the 12V air pump to cut off at like 65lbs. Then I adjusted the regulator to 55-60. Potty worked great...but pocket door freaked out. Lowered air pressure to 40. Pocket door happy, potty not so much.

Ended up with two regulators...One set to 45 for pocket door, and one set to 60 for potty.

I think what is happening is that the regulator is set for 60ish and when you are supplying more than that, it is fine. But with engine off and 120V pump off, the air pressure is dropping to 45ish and the potty is not happy with low air pressure. Adjusting the 12V cutoff to a higher pressure will probably fix.

[bestgenman]

It sounds as if there isn't enough tank capacity.  These coaches have many different hookups, on mine the DC comp feeds the tank in front of the drive axle which feeds the toilet, pocket door, & seals.