[Richard]

Ok,

The toilet flapper and the air door are both supplied from the Ping tank in the rear passenger rear well. I think, but not 100 percent sure that the way that the air system is plumbed is like this: there is a regulator at the 12v air compressor, both the 12v compressor and the supply air line feed into that regulator. That is how you keep the pressure constant on the potty and door regardless of which compressor is running. 

So, the door closing slowly and the potty flapper not closing are signs that the air pressure is low at the regulator. Find the regulator at the 12v air compressor and read the gauge on it. Increase the pressure and see what happens. I don't remember off hand what mine is, but I think it's about 60 psig. 

So for Shamu here is an explanation of how the 12v, 120v, and engine compressor are all tied together.  The engine compressor obviously supplies pressure to all systems, feeding first to the desiccant cartridge in the driver tag well before going into the "wet" brake tank and then on to he rest of the tanks. The 120v compressor supplies air into the overall system too. I have seen different ways that Newell used to tie in the system to the 120 compressor. The 120v compressor is usually set to turn on around 70 psi and off at 90 psi using a garden variety we'll pump switch usually located in the generator blower housing bay. And then there is the 12v compressor that feeds the wheel well ping tank only. There is a check valve that keeps the 12v compressor from supplying the rest of the system, but allows the engine compressor or 120v compressor to pressurize the Ping tank.

Back to Shamu's initial problem. Let's check that proper air pressure is present before tearing into the system.

As usual, I'm often wrong but seldom in doubt.