Air Compressor shuts off and all the air leaks out

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In response to an earlier post, Matt posted this. I have the same issue… sort of. My compressor will run up to 125 PSI, it will shut down, and then the unloader valve leaks and leaks. The kicker on mine is that the compressor will not kick back on until the tank is completely empty.

The compressor tries to start with air in the tank but blows the breaker. When the tank is empty, the compressor starts right up and runs perfect up to 125 PSI, then it shuts off, it leaks, it won’t start at the normal cut in, but all the air leaks out, then it will start and run up to 125 PSI, shut off, and the cycle repeats. Please help. Matt.

Compressor tank check valve


Well Matt, the first thing we would do is, with an empty tank and the compressor off, pull – test / clean – or replace the tank check valve. It is likely that the failure of the tank check valve to shut completely when the compressor is off that allows the air in the tank to continuously leak out of the unloader valve.

Get that one resolved first. That should stop the leak. Then, we can address the fact that the compressor will not start unless the compressor is empty. Let us know, okay?


Matt responded… you are the man. Cleaned out the check valve. Part of the O-ring had ripped loose and was stuck in the spring assembly. I cleaned it out. put in a new O-ring, and she works better than she ever did before. Thanks!


Glad to hear it, Matt. If you need some guidance on the not-starting issue, my suggestion is to check the start capacitor! Let us know how it turns out if you would.

By Ashley Pearce

As a passionate manufacturing and mechanical engineer, I've had my fair share of run ins with air compressors and compressed air systems. With over a decade of experience in the industry, I have both a fresh perspective and time-served hands and mind to help you with your compressor problems (along with our able community!)

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