Harbor Freight compressor will not shut off?

by Kevin
(Tyler ,TX)

I have a central pneumatic oil-less compressor (3gal oil-less) compressor that builds to 40PS but won’t shut off also at what psi is it supposed to shut off?


If yours is the “3 gal. 1/3 HP 100 PSI Oilless Pancake Air Compressor ” then the normal cut out will be 100 PSI.

Harbor Freight - Central Pneumatic Pancake air compressor

Harbor Freight – Central Pneumatic Pancake air compressor

Not knowing the model of compressor makes this a bit more complicated.

Howe about looking on the troubleshooting page and reading the pages about HF compressors, and other brands, don’t build pressure?

When you’ve done that, pop back here with a comment about what model you’ve got and what you found when you did the checks.


Harbor freight 21 gallon compressor runs constantly

by Konner

I have a harbor freight 21 gallon compressor and I accidentally popped of the pressure switch.

I thought I got it back together correctly but now the compressor lever to turn it from AUTO to OFF does nothing and the compressor runs no matter what the lever is on.

The pressure switch brand is Lefoo.
Lefoo is a common brand of pressure switch.

If, as I understand it, you somehow disassembled the pressure switch and you cannot reassembled it (no shame there, I couldn’t either), you can get an exact replacement many places on line.

When the compressor is running, does the tank pressure continue to rise to the point that the PRV releases? That being the case, get the pressure switch changed sooner rather than later, as your air compressor is in a dangerous configuration.


by: Konner

Yes, you are correct. I accidentally disassembled it and apparently I didn’t get it back together right. I let it run until about 140psi then shut it off because it is supposed to shut off at 125psi. Thanks for the help.
You are welcome. For safety’s sake, get a new switch on the compressor sooner rather than later, will you?

Or, if you want a challenge, check out the page on putting a switch back together linked from the troubleshooting page on this site.


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