How to fix an air compressor that won’t stop

Last Updated on by Brian A Cummings

How to fix an air compressor that won't stopIn some instances, you will encounter your machine seems tireless, meaning it doesn’t want to turn OFF. Other air compressors, due to age, need that extra push to the switch just to turn OFF. However, if the problem lies in the continuous pumping of air to the air compressor tank and generally it won’t stop, this is a serious alarm. You should address this problem immediately before using the machine again. So unplug the machine and diagnose the problem.

Remember that even if you think you have the best air compressor at hand, if improper handling, aged, and it’s not maintained well, it can still dysfunction at a certain point. Here are the possible reasons why your air compressor won’t stop:

Check this out: What’s the Difference between a Single and Two Stage Air Compressor

The cut out pressure setting level

One control that automatically stops the air compression process is when the pressure inside the tank reaches the cut out pressure setting level. This means that the tank is full and is ready to use. And once there is a decrease, then the air compressor will start pumping compressed air into the tank. A complex, well-coordinated, and fast process, which lets you think it’s very simple.

However, when there is continuous running of the air compressor to fill the tank, even if it already reaches the mark, then there’s really something wrong. A normal mechanism of the air compressor is to balance what’s inside by releasing some to the atmosphere through the PRV. But, this does not solve the problem. Since the small air compressor still runs, and when not stop it will contribute to its deterioration and eventually breaks.

The pressure relieve valve

As described above, the PRV acts as the equalizer to maintain just the enough pressure inside the tank. This is also known as the safety back up of any air compressor. The PRV is set to activate, and the level is higher than that of the cut out pressure setting level. So when the cut out pressure setting level doesn’t stop the air compressor from working, the PRV will then handle all the excess air pressure by opening the vent to let some air out. However, if this does not work, then there could be a more serious problem at hand. In this case, do not use your portable air compressor until the necessary repairs have been made.

The pressure switch

The common pressure switch according to air compressor review is the Condor brand. The compressor switch functions to turn off the air compressor when the tank pressure is already high and reaches the cut out pressure setting level. You should be familiar of the PSI of your air compressor. The common range is between 100 – 175 PSI. So, if the pressure inside your air tank is becoming higher and higher, you are sure that your pressure switch is not working.
What should you do then? Replace! Of course, this certainly is a challenge since finding the pressure switch might be hard. There are few stores that sell this part. So it is advisable not to look for the branded one, but look for the compatible type (the one that fits perfectly), unless your machine is still under the warranty period.

Here are the things you should consider when buying it: compatible size, it fits snugly to the unloader valve, with the same voltage, and has the same cut with the original cut out pressure switch. If you will be able to provide the pressure switch that meets the following criteria, then you are on your way to a successful repair of your air compressor.

Other scenarios

Well, the bad news is that there are other factors that contribute to why your air compressor continues to run. One of which is when your air compressor is not able to pump the necessary air to reach the cut out pressure switch level. This means that the air compressor is only able to pump below the cut, for example, only 20-80 PSI is reached. And this happens even though the air compressor is running. This can result to the breakdown, destruction and/or overheating. But, you may be wondering how could this happen? It could be because of the failure of the intake valve and pressure valve, a broken gasket inside pump, or an impeding flow in the tank check valve.

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10 thoughts on “How to fix an air compressor that won’t stop”

  1. Hi. I have a C2002 that is supposed to be 150psi. However, the tank gage doesn’t go oer 90psi (with or without hose & attachements) and runs until I shut off the power. Any ideas what is wrong? I have until 1/30/2017 to return it to Amazon.

    • The higher pressure design provides longer air tool performance and features a 2.6 SCFM at 90 PSI allowing for a quick recovery time. You have to adjust the pressure

      • I finally got it up to 150 PSI and it shuts off itself. It seems air was escaping but with the noise, I could not hear it. Now I can save time restoring old computer and server parts.

  2. I have a husky 516-051. I’m having a continuous run past the 150 cutoff, straight to the PRV. Tried a new pressure switch but same problem. Had a compressor expert come over and tested the switch and said it was bad. Bought another and same problem. Everything else seems good. #confused

  3. I have a husky C303H I have replaced everything on this compressor from the switch to the compressor . My problem is it will start running with the on off switch off or on ant it will not stop running until the pop off valve gives . Ive put 4 pressure switches on this and nothing seems to help any Ideas

  4. I just bought a used dewal t 15 gal 200psi 1.5 hp. The air tank gauge reads 200 psi when empty when I let it build pressure the gauge will rise up an goes past 350 psi on gauge so i stopped it. I’m not sure if it will shut off when max is reached. Since the gauge reads 200 empty and when I shut it off it was at 350-375 psi so thats aboutb175 psi in tank if guage reads well even since its not at 0 on empty how can i fix this should i just buy a new gauge

  5. i have a porter cable jetstream 2 stage 80 gallon tank, it blowed the prv , replaced the pressure switch with a exact replacement and replaced the prv,compressor cuts of @175 cuts on at 140, switch was rated 175 cut off but after replacing switch and prv,same problem,prv is only rated 165 but i don’t think that is the problem,always worked fine til it exceeded pressure and blowed prv,any help would be appreciated, i make a living with my compressor,don’t really want to buy a new one, still build up air great just will not shut off

  6. I have a Ingersaul Rand 60 gallon single stage and it will run until the motor trips and only will only reach 100 psi. Just curious if anyone else has had this problem I’m thinking the compressor gasket?

  7. I have a Porter Cable C2002 Type 7 1 HP 6 Gallon Compressor. I installed a new pressure switch. The compressor runs for a few minutes and died again. Is there anything that may cause the switch to burn out. I did smell an electric burning smell. I don’t want to try another switch before making sure. Thanks for any info to help me with the issue, Sig.

    https://www.ereplacementparts.com/porter-cable-c2002-type-gallon-compressor-parts-c-129_1662_168374.html

  8. If I can save some of you some work: results of research a finding a great review:
    My 20 month old Porter Cable C2002 Type 9 only pressurizes to 100 psi, does not shut off.
    It was in a dusty (gritty) location. Most of these oil-less compressors do NOT have air filters.
    So it appears that I most likely have a cylinder not capable of reaching the cut-off of 150 psi, with a worn Teflon ring. Replacing the connecting rod assembly ($33) and the effort to do the work are far more than the $99 compressor is worth. (Truth be told, was not impressed with the low SCFM and the noise of the C2002, either)

    Master Tool repair has a great oil vs air comparison review video: https://www.youtube.com/watch?v=qhwmwQawV0w

    I’m going with a Makita MAC700 as a replacement.

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