Air compressor wont turn off in the auto position

by matt

compressor wont turn off when the switch is in the auto position.It will turn off in the manual position.

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Aug 03, 2016
Draper compressor won't shut off
by: Bill

I don't know to which valve you refer, Des.

Did you do the check as suggested in my reply to the April 2015 post?

If the pressure switch is still allowing power to the motor circuit after the cut out pressure level is reached, it's like the pressure switch that is the problem.

Aug 02, 2016
Draper 150lt
by: Anonymousdes

Hi Bill

Compressor keeps going until it reaches max then blows off to 60 psi then starts up again.

I've replaced the value and it's still doing the same.



Apr 13, 2015
Clarke 2hp 4 gal. Keeps running
by: Bill

If the compressor keeps running past the normal cut out pressure setting, then the pressure switch is not tripping to off, and the power keeps flowing to the motor circuit.

So, this were mine, it's time for a new pressure switch.

To check, dump some air from the compressor tank to below cut in, with the compressor off.

Open the pressure switch cover, and with care, power up the compressor. The points inside the pressure switch should move when the tank pressure reaches cut out.

If they don't I would suspect that the points are fused.

Apr 12, 2015
Clarke 2hp 4 gal. Keeps running until prv
by: Eric

Hi Bill,
My issue is per a) in Matt's trouble shooting request of air compressor won't shut off. My compressor runs until pressure hits red line and then prv lets out the air and it starts all over.

What do I do to fix?


Nov 05, 2014
Compressor won't turn off
by: Bill

It would be good to know the make and model, Matt.

OK, if it's in the auto position, that means that the air compressor ON/OFF is controlled by the pressure switch.

If you aren't sure what that is, see the pressure switch page on this site for details.

When you say the compressor won't turn off on auto, are you saying that....

a) the air pressure in the tank continues until the PRV lets go

b) the air pressure in the tank reaches a certain pressure level which is below the normal cut out, and goes no further

We need to know which.



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