air pressure loss

Might have been better if you had posted in the right forum. I asked mod to move it for you.

Build up air pressure, turn off engine and crawl around and listen. You will find where the leak is.

If it is a fast leak once you pressurize you will more than likely be able to hear it. Or if not then soapy water in a bottle and start squirting all the fittings by the air tanks and at all the air lines and fittings.

To check if the air dryer has failed, open each of the tanks DRAIN VALVES. If anything but clean, dry air comes out, the dryer has FAILED.

But, that may have caused your issue, but is unlikely to be the issue causing the leak.

Best advice, with proper jack stands in place, go under the coach with a spray bottle (kiddie bubbles and water are best). Spray every connection and valve. If it blows bubbles, fix it.

Yes, if the leak is large enough, as soon as you shut off the engine (i.e. air pressure at max/cut-out PSI) you may be able to hear the leak.

thanks for the replies, guys
Paul

A tip on locating an air leak: get a several foot length of tubing from an old water hose or something similar and use it as a shade tree mechanic stethoscope to locate air leaks. Check all connections and places where the plastic air lines are not sufficiently insulated and could possibly rub through.