CAP60P-OF no pressure & whistling sound

by Ric Hall
(Somerville, AL)

CAP60P-OF all of a sudden lost pressure after running.

It will usually hold pressure for a day or so before the pressure bleeds off.

This morning it bled off in a few minutes. Then later I turned it on just to nail a few small brads. I was able to do this, but pressure never went over 70 psi.

There was a high pitched whistling noise. this noise was also made each time I turned the compressor crank by hand.


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Jul 05, 2015
Line from compressor tank
by: Bill

That line is likely the unloader valve line.

Air should escape from the unloader for a second or so when the compressor stops, and if it continues, then the tank check valve is still not sealing.

See the troubleshooting page on this site about air compressors that run but don't build pressure for things to check about this problem.

Jul 04, 2015
Checked tank valve still min. pressure
by: Ric

Bill: I checked the tank valve & did find a bit of metal shaving on the seat of the valve. I removed the shaving & reassembled. Compressor now runs without whistling noise, but tank pressure never gets above 10 psi. I replaced quick release valve because it was leaky. I notice air coming from the small plastic line that runs from the tank valve to the pressure switch box. Is this normal? I cannot tell what the function of this line is or if it is working properly.

Jun 28, 2015
CAP60P-OF no pressure
by: Bill

First thing to check, based on your compressor symptoms, is the tank check valve. Please do that and then add a comment here letting us know what you found.

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