Here's another idea....look up in front of the RH front tire and you'll see the front leveling valve that is mounted on the Kneeling valve. The kneeling valve is likely causing your problem. It'll exhaust all your air faster than you can make it. Turn the wheels to the right, grab a hammer and whack the kneeling valve...DON"T whack the leveling valve or any air lines...!
The kneeling valve is a large cast iron valve on which the front leveling valve is attached. And if that solves your problem, never again use the kneeling feature. Don't just disconnect it though...it has an interlock and you don't want get involved in that unless you know exactly how the kneeling system works. It's complicated to say the least.
The door switch is next to the kneeling switch, but the kneeler is covered by a bomber door. Leave it shut.
The kneeling valve can be removed, but you'll have to replumb the leveling valve. I eliminated the kneeling valve and the front leveling valve from my NJT. Use a regulator to control ride height. The rear is still on leveling valves, but the weight of the front never changes (unless of course you could afford to fill the fuel tank...and no one has that sort of cash!) on a conversion, so all one has to do for a simple and very dependable front air suspension is to take control. About 60 lbs will give you a nice factory ride height.
You might also try playing with the kneeling switch and see if it shuts off. The kneeling valves wern't used much and crap causes them to fail. Hope this is your problem....could be a blown air suspension bag, failed air beam if you have an 83...and it could be any air line or tank located under the front (that is where the air is leaking?), If you were dinking with the kneeler, it's probably your problem, if not...
The exhaust for the kneeling valve is the sintered brass (don't hit that either) thingy on the kneeling valve.
As others have described, the air tanks drains may be leaking, but if air is leaking in profuse amounts, check the kneeling valve.
The shop air should supply enough air to raise a badly leaking bus so that you can get jacks under the jack posts. That's a start.
Post a descripition of what component exactly you find leaking and we can be more descriptive regarding repairs. By turning the wheels to the right, a smallish person can crawl into the area between the RH tire and the frame...find out what is leaking.
I doubt that the brakes will release unless the leak is remedied...not really sure about that.
Good luck, JR