[BusNit]

Yes on the check valve. It takes some pressure off the compressor and avoids bleed down, keeps the engine air brought up to 110psi and helps the aux compressor to start under load although that load should have been released at the air pressure cut-in/out switch. On my coach if I plug in to shop air, say around 120psi, the aux compressor cut-in switch will bleed out anything over 100psi. At first I thought I had another air leak but it was just doing its job. On the new compressor install, I put in a 1/4" high temp flex lead that about 12 or 18" to go from compressor to auto-drain water separator. I figured the hot air from the compressor head might deteriorate anything else used unless it's hard pipe. My new Gast developed leaks around the head so I gave up on it. Was an expensive affair as I thought Gast was the best in the business. If the California compressor lasts at least 3 years, then it's a cheap bargain and easy to swap out. (California Tools MP100LF) Mine runs on 120v and I didn't want to exceed the original amperage of the coach's wiring of 7 amps.