I thought you said yours worked great. Did you mean just for car tires Lee?
I hope John is making headway with all the options we've offered. The Lowe's home-built as per the video device adds up in cost, but certainly works. I'd like to see someone address his leak problem, as I agree with Tic that he probably shouldn't be loosing that much tank pressure so quickly. Problem is it could be lost from any of many places. Others more experienced here might offer some guidance as to the more likely culprits and places to look first. At that rate, in quiet ambient conditions wouldn't he be able to hear the source?
I guess I'd first see that my 4 air tank drain valves are all closed fully - on mine they are just left of the battery tray. Then I'd start the engine, make sure the tranny's in Park and brake set, and fill the tanks, shut off the engine, and first listen under the stairs, in case the stair air feed is compromised. Check that the auxilliary Quick connect, near or with the 4 drain valves, isn't leaking due to debris blocking its valve or a bad connector. Some coaches have the Quick connect up front in the genset compartment, but you've already found yours obviously, John. After that it comes down to the ride height control valves and airbags I'd think.
If you get under the coach, be sure you've placed adequate blocking so the coach can't come down on you, especially if air is being lost and you are messing around with valves. Better yet, take it to someone better equipped to check such things.
Joel