I heard a light hissing noise coming from the rear passenger side well.
ah ha! the air tank is situated under the body about where the rear passenger door is.
Leave the vehicle on jack stands and check the nylon air line connection into the tank for leaks...use soapy water. If it is leaking, you will need to trim the end of the airline and replace the o-rings. Check around the screw in plug in the tank for leaks also.
If there's a leak... then: CAREFUL! :hand:
Open the the screw in plug slowly about 2 turns, no more.
There is a channel machined at right angles to the thread which allows you to bleed pressure out. Once the tank is FULLY exhausted, remove the screw plug, check for residual water, dry any that's there with a rag and clean the threads. Put some thread sealer on and replace the plug. do it up snugly, don't over-tighten.
Remove the airline from the tank and trim the end (just a couple of mm), replace the o-rings in the tank connector, push the airline back into place ...you'll feel it push past the initial resistance of the o-rings and see if you can reinflate the tank. check for leaks.
It IS frustrating... but worth the effort once you get it working. :thumb: