Yep. You got leaks in the air system, or the compressor is failing. As already stated, drain your tanks and see what comes out. If no oil, leaks are the likely culprit. The NJT dryer should keep the tanks dry...if it's working properly.
I've got an identical coach to yours and when the compressor kicks in on mine, it just climbs right up. Never have to wait for air unless starting cold. And I got leaks too.
Get a bored child (or young babe!
) to listen for leaks. They can hear them surprisingly well.
A 24V fuel gauge will be hooked up with 24V to "ignition" terminal on the guage, ground to about any part of the guage body, and the 'sender' terminal lead to the sender center terminal. Your NJT has the fuel guage wiring appropriated for the fuel primer pump. I'd recommend restoring the fuel sender lead by disconnecting it in the ACJB (upper LH front bay) and reataching it to the fuel guage wiring...which is in your bus.
The sender for an MC9 tank is proprietary and nothing else that I know of will interchange.
The water temp guage and voltmeter both have 24V that can be jumped off the stud. There's a ground bus (stud) right next to the fuel guage mounting hole (RH dash).
The sender ground wire is taped up just to the right side of the fuel tank. The ground wire should be attached to one of the 5 sender mounting screws.
Once electrically out of the system, the primer pump can be used directly from the batteries with a 4' jumper if you need it. I'd definitely keep the primer pump servicable, just rewire as necessary. And the momentary primer switch should be tossed. That's a PITA to use. Just use an alligator clip on a wire. You won't leave it on overnight if you cannot close the fuel and battery compartment doors!
If you wish to run a new lead for the fuel guage, the best route is thru the battery box, into the front bay, across to the small tunnel which will route the wire right behind the drivers seat area, and then thru the bottom of the side switch panel and into the dash. Pretty easy to do.
May I suggest you buy a good quality fuel gauge sending unit. The cheapos will fail due to terminal rust when sitting. I bought an cheapo and it failed after one year of use. Bought the second unit from US Coach and it has been in the coach, and working, for 2 years now.
The sender is always above the fuel level...so it's ripe for rust.
And I keep my fuel tank full.
Good luck on that door! I had to pull the RH upper SS panel to facilitate welding the hinge in place. Breck was able to weld his from the dash? The dash will have to be cut out for the limit arm anyway...cut it out first and you'll have a good deal more room to visualize your work area.
Install the air lock too. The box is already there. The air solenoid for the bi-folds can be used to control the air lock. Check the solenoid for air leaks. Most leak.
The door is too heavy to latch into the middle of the door jamb when under way. The door isn't designed to be latched from the middle anyway.
The center door frame is OK for a campground latch.
Note that the upper door hinge bolt is threaded thru the uppe hinge. This allows vertical adjustment for the door. BE SURE THAT THE LOCATION OF THE UPPER HINGE PLATES ALLOW FOR THIS ADJUSTMENT. The lower hinge allows 'tilt' on two planes.
Check the dimensions of the door v the frame before hanging the door. Any RF damage will have to be corrected before the door will close.
Don't forget to leave room for the weatherstripping. That's a bummer when the door is hung, but the weatherstrip won't go in due to lack of clearance.
Sedan doors are really tight fitting. About 1/8" + - is it.
Don't attempt to 'buck' the upper door section with the glass installed.
VERY IMPORTANT: leave a window or hatch open when working on the door. If you get locked out, you want a way to get inside to remedy the situation.
My dos centavos, JR