I fixed a DIY compressor that doesn't cut off

I was given a Porter Cable Pancake compressor that wouldn't cut off. Being new to air compressor functionality, I hit Google. It seemed it was the pressure switch, and I found plenty of generic info for adjustments, but nothing specific to Porter Cable compressors, other than replacement and seemingly people still having the same issue.

After taking the compressor all apart, cleaning, and reassembly, I found the screw for adjusting the pressure switch, a tamper proof Torx bolt.

Firstly, I would recommend replacing this with a like sized conventional bolt/screw. With the switch disassembled I loosened it until the end of the bolt was even with the retaining nut/washer and reassembled. Cut off then worked fine, but at about 100 PSI. I tightened the screw until cut off hit 140 PSI. No idea what it should hit, but being a 135 PSI compressor I thought this was good. I let it cycle several times by pulling the emergency valve and it's consistent.

I don't know if the pressure switch spring gets stuck after awhile, but loosening and tightening again did the trick for me on the original pressure switch.

I had seen several people replace the switch, only to have the same issue, it not cutting off. I didn't mess with the cut in adjustment, and was hard to pinpoint using the emergency blow off valve but seemed to be about 100 - 110 PSI.

My intended use for this compressor is for an airbrush, so I want to play with the cut in adjustment (which is covered by a dab of hot glue) and see if I can get that to about 60 - 70 PSI as I don't see it'll need to stay as high for running an airbrush as say nail guns.

So, hopefully this helps some people to save money before replacing that pressure switch.

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Mar 19, 2017
CFFN250N & T20
by: Anonymous

The model is CFFN250N, and the adjustment screw is a tamper proof T20. Or a T19 maybe? The T20 bit didn't seat fully in the head, felt like the center button but may have been my bit. That's why I recommended changing it, which I will do when I look at the cut-in pressure.

Mar 17, 2017
cut off
by: Doug in s.d.ca.

Thanks for sharing. Good to know.

Could you share your compressor model and size of the tamper-resistant Torx?

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