I have found several "Push-To-Connect" fittings leaking.
These fittings are great for the assembly line as they are fast to assemble, but not so good for servicing. There is an o-ring inside the fitting that leaks. It's also helpful to assembly line that on the 90 degree fittings the head swivels - but that's another place for a leak. I find they are almost impossible to disassemble to remove the hose despite what the instructions say (I end up cutting the nylon air hose flush at the fitting). When testing your air system for leaks, you have to grab each hose and move it around sometimes to see the leak (bubbles).
I have been replacing these P-T-C fittings with standard compression fittings when I find one leaking. I did the rear of coach this year. So far I replaced about five fittings for leaking, and another fifteen or so when I rebuilt my rear HWH manifolds (because the hoses don't release from the fittings as they should).
My next chore is to get under the front of coach, rebuild that HWH manifold and check those hoses/fittings.
