Having trouble with your air compressor not shutting off when it reaches cut off pressure? You’re not alone, it’s one of the top troubleshooting questions we get on this website. I’ve pulled together some of the top questions and answers I’ve given helping to troubleshoot compressors that just won’t stop!

Table of Contents

My Air Compressor Won’t Stop Running

by Rick

My compressor will not stop running. It builds up pressure, but keeps on running. I think that it needs a new regulator but I am not sure.

Answer

Hello Rick.

What you don’t say is if the pressure in the tank reaches and bypasses the cut-out pressure point?

If the compressor keeps running, and the pressure in the tank passes the cut-out point, then eventually your PRV is going to operate to vent pressure inside the tank before it reaches a dangerous level.

If the PRV is sized correctly, then it will vent air faster than the compressor can compress it, so ultimately all of the air in the tank will vent safely.

Your compressor, however, will continue to run since it would appear as though your pressure switch has failed, and since the unit can’t ever reach cut-out, then it will eventually self-destruct.

If it’s the above scenario, then in my opinion your compressor has a serious situation with your compressor, and you should stop using it until you get it fixed. If the PRV fails too, there could be a dangerous over-pressure issue.

For the above I suspect that the pressure switch may be at fault.

If, on the other hand, your compressor reaches a pressure point BELOW the normal cut out pressure point, and the compressor keeps running but the air pressure doesn’t pass this point (say 70 PSI for example), then it’s not the pressure switch. That typically points to a valve or cylinder problem then.

Either way, your compressor will do itself serious damage if it runs past it’s duty cycle or over pressurizes.

Hope this helps…


Compressor won’t shut off and pressure won’t build – compressor keeps running

I have a sears air compressor that builds pressure up to 60 psi and keeps running but builds no more pressure. It used to build pressure up to 120 psi and then shut off until the pressure would drop.

Answer

Hi Jerry.

When a compressor is running it’s dumping air into the tank, and when the pressure in that tank reaches the cut-out pressure setting, the pressure switch trips, and the compressor stops.

In your case, as I understand it, the compressor cuts-in at the low pressure point, and pressure starts to build in the tank until it hits around 60 PSI, and then, even though the compressor keeps running, the pressure won’t build further?

First off, eliminate any leaks. It’s hard to hear a leak when a compressor is running, and it may be a small leak that the compressor can overcome until it hits that 60 PSI range, and then the leak intensifies and the compressor can’t get past that pressure.

No leaks?

If you’ve got no leaks, then it would seem reasonable that the air seals are worn to the point that the pressure can’t get past the 60 PSI point due to blow back between the piston and cylinder wall.


Compressor motor won’t turn off keeps trying too run when full of air

Question: motor wont turn off keeps trying too run when full of air

Answer

If the compressor motor is still running after the air pressure in the tank reaches the normal cut out air pressure level, then look to your pressure switch first as the source of the compressor problem.

If the air pressure in the tank doesn’t reach the normal cut out pressure level, and since then the air compressor can’t shut off as the pressure never reaches the cut out pressure level, then look to the intake valve or internal gasket leak as the possible source of the problem.

If the air pressure is bypassing the normal cut out, I recommend that you get the pressure switch looked at or replaced before using the compressor again.


Compressor won’t shut off automatically?

by Mike
(Fredericksburg, Va.)

With Switch set on automatic no matter what pressure I have the regulator set on the Campbell Hausfeld air compressor never cuts off until I manually turn it to the off position…..The compressor is a 20 gallon tank, 5.0 HP, 135 max. p.s.i.

Answer

Mike, I am having a bit of trouble understanding your terminology.

The switch that’s on “automatic” is the pressure switch setting, yes?

The regulator you refer to, is it the one with which you adjust the downstream pressure to the air line and air tools? If so, that regulator has nothing to do with whether or not the air compressor cuts in or out.

That function, compressor ON and OFF is the job of the pressure switch, and if that switch is set to automatic, and the compressor runs until the tank pressure bypasses the normal shut off pressure setting, then it’s a good bet that the pressure switch has an issue. You may need to replace it.


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