Vinney says… “I’ve taken my 3 gal compressor and removed the compressor from the tank.
I then put an old refrigerator compressor on in its place, but now I’ve got air leaking from the unloader. It won’t allow the air into the cylinder to compress. Is it because of the low air flow? a bad check valve or the unloader?”
Willyr says... I would think that if you have air leaking from the unloader valve that it is the tank check valve that is the problem.
When the air compressor is off and the unloader valve is open then it is the tank check valve that keeps the compressed air in the tank when the unloader opens to atmosphere.
A refrigerator compressor pump likely has no need for a tank check valve as it is a completely closed system with no way for the refrigerant coolant to get to the atmosphere, therefore, no check valve to keep the coolant in the heat exchanger.