pressure going too high - PRV blows

by Scott
(Dulles)

The compressor is exceeding the required PSI then blowing the relief valve.


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Bill says....

Scott, the likely cause is that your pressure switch has failed on the high pressure cut out.

It were mine, I wouldn't use the air compressor again until I had replaced the switch and/or resolved the issue.

Loss of the high pressure cut out leaves only the PRV to protect you from a potential catastrophic event, and for me, that's not enough protection.

Cheers,

Bill

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Won't turn off automatically

Unit starts whrn pressure is zero, but won't turn off.

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Bill says....

Is it that your compressor turns on at low pressure cut in, then the pressure builds past the normal cut out level, and keeps running and building pressure until the PRV pops?

Or is it that the compressor pressure level builds to a pressure level below the normal cut out, and as a result, the pressure switch never senses the cut out pressure level and the compressor keeps running?

If the former, look to a faulty pressure switch.

If the latter, look to the TROUBLESHOOTING page about "COMPRESSOR WILL NOT BUILD PRESSURE".

Cheers.

Bill

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Porter Cable Job Boss compressor will not stop running (not pressure switch)

by Ryan
(VT)

Hello: I have a Porter Cable Job Boss compressor, that will not stop running. I actually have two, one that works fine. I took the pressure switch of the working one and tried it on the one that would not shut off. No luck it will still keep building pressure.

Any Ideas? Thanks Ryan

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Bill says...

Ryan, it is the pressure switch that turns the power off and on to the motor. If the motor continues to run to the point where the PRV valve lets go, then that power has to be coming from somewhere.

Put a multimeter on the power line from the switch to the motor when the pressure is past the normal cut out pressure level. If power is still flowing to the motor, then the pressure switch has not tripped off.

That may be that you are really unlucky and the second pressure switch has failed too, or, it might just mean that you wired the replacement incorrectly. You need to check that out.

Cheers,

Bill

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