The tank check valve an image of one which is shown below is typically located where the air line from the pump head enters the compressor air tank.
Air compressor leaking check valve.
Also helping understand what check valve t.
There are a few things that you can notice if you have a damaged check valve in your compressor.
Air continuously leaks out of the unloader valve on your air compressor and this is a problem.
If it is no longer keeping the air in the tank due to it leaking then the tank full of compressed air flows out of the unloader valve too until the tank pressure drops to the cut in pressure.
These are air leaking from the compressor.
Well if air continuously leaks out of the unloader valve then the compressor tank is emptying and the compressor needs to restart to replenish the air in the tank to get back up to cut out pressure so it can stop on its own.
Identification of a faulty check valve in air compressor.
When you are not working with the compressor air should not leak from the tank of the compressor.