921.166400 won't get to the 125 shut off

I have a 12 gallon 1hp craftsman. # 921-166400 It won't get up to 125psi cut-out pressure. It only gets to 100psi and keeps running. I replaced the pressure switch and it is doing the same thing.

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Aug 23, 2017
921.166400 running on and on
by: Bill

It's not the pressure switch, friend.

The troubleshooting pages on this site about air compressors that run on and on but don't build pressure will point to valve issues, piston rings, compressor motor problems as all possibly being the cause of your run on 921.166400.

Since I don't know what you've looked at using those troubleshooting pages as guides, I am not quite sure how I can help further.

Again, it's not the pressure switch. That only works when the pressure falls to Cut In, and then reaches the Cut Out pressure setting. If the pressure never gets to the Cut Out setting, your compressor will run until it shuts itself off on thermal overload.

Please provide a few more details about what you have checked per the guidelines on this site.

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