Recently I put together an air compressor for airbrush use, it had a silent compressor motor on it from new. It was to loud for use in the evening, so I out two refrigeration compressors on it instead, the compressors work fine. But the pressure switch just leaks air from the unloader valve, so I bought another pressure switch in the hope this would cure it. And it hasn't, it's still leaking air from the unloader valve.
Also I have removed and had a good look at the receiver check valve, the spring and valve seat look fine. I am at a complete loss as to why the unloader valve is leaking air, and not filling the tank. All I can come up with is the two refrigeration compressors don't put out nearly as much air volume as the original compressor twin piston unit does. If there are any air engineers out there that might know what's going on with the unloader valve leaking air ? I'm starting to think I'm going to have to think up another type of air control system. But I've watched all the YouTube videos on this similar projects, and there using the same pressure switch, and have no problems. Thoughts appreciated, thanks for reading. The pressure switch is the common one with the pull push on off knob on top of the pressure switch housing.