Joe,
"Second question which compressor keeps the bladder full?"
I'm assuming your reference to the "bladder", you are asking about the slide seals. On your vintage coach, there are three air compressors. The simple answer is that any one of the three will inflate the slide seals.
Here is how it works. The 12Volt compressor will put around 60 psi into the air tank in the right rear wheel well and energize the toilet(s), air pocket doors, and slide seals. The small compressor is isolated from the rest of your coach's air system by a check valve located on the previously mentioned air tank.
The 110Volt compressor will produce up to about 110 psi and energizes
ALL systems in your coach. Once the 110 compressor psi rises to above 30 psi the check valve on the RR wheel well air tank opens and the compressor also produces air for the entire 12V system by sending the air through the 12V compressor regulator, which is located on the 12V air compressor.
The engine compressor produces about 120 psi and energizes the entire coach. It will fill the brake air tanks to about 60 psi before it begins filling
ALL of the other air systems of the coach. It energizes the 12V system through the before mentioned check valve when the coach air system goes above 30 psi.
See this very crude schematic:
http://newellgurus.com/showthread.php?tid=2674
Hope this is helpful................................