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.

Comment here with any more info.



Comments for harbor freight 21 gallon compressor runs constantly

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Nov 29, 2015
What pressure switch
by: Bill

Find your compressor model number, and then Google pressure switch for that model number and you will usually find sources. Since I'm not sure your model number, I cannot recommend a particular one.

Nov 29, 2015
Did same thing.....help!
by: Allen

Can you tell me where u got the new switch please?!

May 07, 2014
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?


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