[rheavn]

"My BIG question is how do you find out the schematic for the air system in a Newell Coach?"

The only manufacturing issue I have with Newell is their system documentation.  Country Coach had outstanding documentation that included system schematics.

So to answer your question, as I isolated separate parts of the air systems I produced my own set of schematics for my coach.  I found that determining what wasn't leaking was just as important as finding what was leaking.  Every leak I found was either at a coupling or an air system component.  I replaced all "push in" type air fittings as I found them & replaced them with DOT compression fittings.  I replaced several air system components that were leaking which included two slide room shut off valves, the air system relief valve, the tag axle solenoid, two air dryers, an air tank, etc.  

Newell's standard for the air system is that the air compressor only runs about once an hour.  As I worked on my system I wanted and achieved losing less than 5 lbs per hour.  The other thing I learned in my project was how the three separate air systems are interrelated and work together.  Unfortunately fixing air leaks is not a permanent fix.  As we take our coaches & put them into earthquake forces more leaks will develop.

To completely go through the air system was not a hard job, but does require time (it took 15 days), patience, the tools in the provided link and access to the underbody of the coach.

I hope my answer was as BIG as your question..........................................