[rheavn]

John,
You spoke with Jimmy at Newell.  Did he describe the 12V & 110V systems as being totally separate?  I only use my 12V air pump when I have my coach in storage.  The rest of the time I rely on the 110V air pump and engine compressor to keep the coach aired up which includes the systems supplied air by the 12V air pump.  If Jimmy meant that the 12V system is separate going from the 12V air pump I would agree.  But the air going from the engine compressor and the 110V air pump pressurizes the ENTIRE coach air system.  The 12V air pump is too small & would burn up before it could pressurize the entire coach.

As a test I went out and drained all the air from my coach.  I turned on the 12V air pump and the 3 gallon air tank in the right wheel well filled and the regulator in the AquaHot bay went to 60 psi.  I checked the brake system & supply air gauges and they were still at zero. 

I then redrained the system & turned on the 110V air compressor, but left the 12V air pump off.  First the brake system pressurized.  Then the auxillary air system AND the items supplied air by the 12V air pump pressurized.  Now how can this be.  There are check valve(s) that allow the 12V air pump to just pressurize a few items, but allow the engine compressor and 110V air compressor to pressurize all coach systems.

I hope this experiment helps you & others understand the air system...........................  

You wrote, "Was too busy today to crib it up, and drain tanks, but hopefully by the weekend. Hope that is the culprit."

Water is just the first problem.  Once you get water in your tanks, rust begins forming.  Now small particles of metal are being pushed through your system.  Both water and the rust play havoc on the air valving.  As Michael said he actually had an air tank rust out.  I had a leaking tank too when I first got my coach and had to replace it.  You may have to do more than just drain your air tanks.  It's just that draining your 10 air tanks and changing your desiccant filter is the place to start.