If your air compressor seems like it’s been running for longer than it usually does, then that is a clear indicator of a problem with your equipment. There are several reasons why an air compressor will not shut off, but there are a few common ones that are worth mentioning.

The most common reason an air compressor won’t turn off is due to a stuck pressure relief valve or a bad seal elsewhere in the system. Some other common reasons are bad seals inside the motor or the motor itself beginning to fail. In some cases, a low-quality extension cord will prevent the compressor motor from getting the power it needs. 

In this article, we will cover all the common reasons why an air compressor will not stop running. We will also discuss some things you can do to resolve this problem.

How Air Compressors Shut Off Automatically

Before we explore why your air compressor won’t shut off, let’s first discuss the turn-off mechanism of a properly functioning machine.

Air compressors automatically shut off at the maximum cut-out pressure. For example, let’s say your compressor has a maximum of 160 PSI. When the air pressure in the tank surpasses 160 PSI, your machine should trip the pressure switch. This turns off the compressor and prevents overpressurization.

If this doesn’t happen, there’s something wrong with your air compressor.

Why My Air Compressor Won’t Shut Off

Air compressors need time to cool after they work hard. That means if your compressor won’t shut off, it may need more than just a quick fix; you might have to wait for the machine’s internal parts to cool down before trying again.

This is especially true if you use an oil-free compressor because these machines require less cooling time than other compressors. However, if waiting doesn’t work- something more serious may be wrong.

Here are some common reasons why your air compressor may not be shutting off:

  • Faulty pressure switch: The pressure switch that requires the right amount of pressure to shut off might be broken or reading incorrectly.
  • A leak: Confirm whether or not there is a leak by listening for hissing or looking for holes on the side of the tank (leaks can be fixed with special equipment).
  • Pressure relief valve damage: Inspect your pressure relief valve; it might be stuck open, allowing gas to flow out when it shouldn’t be.
  • Dirty filters: Check your filters- they may need changing due to dirt/debris buildup, causing other parts to fail.
  • Malfunctioning air tank gauge: The air tank gauge might be broken due to corrosion or even dropping something on your machine.

Let’s check out some brand-specific troubleshooting steps to get your air compressor back up and running in no time. Look for your brand below!

Other Reasons The Compressor Won’t Shut Off

There are some circumstances where an air compressor motor will run forever. For one reason or another, the stop signal is not getting to the compressor. .

There are several different systems in an air compressor that can start and stop the compressor motor, so we will try to cover the most common ones. 

Not all of these problems are easy to take care of on your own. Something advanced like replacing the internal components of the motor might be something you feel more comfortable letting a professional take care of. 

1.Leaks And Other Simple Cut Out Pressure Problems

An air compressor has a cut out pressure setting. The cut out level is the pressure that an air compressor is supposed to stop producing additional compressed air. Your air compressor knows when the tank is full only when the cut out pressure has been reached.

Under normal operation, when the air pressure reaches a set level and the pressure regulator bleeds some of the air off, which causes a decrease in pressure. Then, the air compressor will turn on again and resume pumping air back into the tank.

There are some scenarios, however, in which things don’t go like they are supposed to. Sometimes, an air compressor will continue to fill the tank after the cut off level has been reached.

Check For Leaks

That is generally the best case scenario because it means you have a leak or some other minor issue. There is, however, another more dangerous failure mode that you should be aware of.

This scenario leaves your motor running which makes it so your air compressor wont turn off. This causes the tank pressure to rise beyond the normal cut out setting.

The good news is that every air compressor has a PVR (Pressure Relief Valve) that will open to vent the pressure. During normal operation, the PVR balances the pressure inside the tank by releasing some of the pressure into the atmosphere.

There are times, however, where the PVR does not work as intended. If it gets stuck closed and the compressor motor keeps running, the tank could eventually explode. The PVR’s other failure mode is less dangerous but just as annoying: 

If the PVR is stuck open it will prevent the tank from being able to reach its cut-out pressure which would cause an air compressor to not turn off. 

Pressure Relief Valve Failure

The pressure relief valve is used to maintain pressure-balance inside the compressor tank could be worn out, damaged, or stuck. The valve is responsible for balancing the pressure inside the tank.

What Is An Air Compressor Pressure Relief Valve?

A safety valve, or pressure relief valve, prevents your tank from exploding due to the pressure of the compressor getting too high.

Whenever your air compressor reaches a critical pressure, this relief valve opens to purge air from the system. An Air compressor’s pressure relief valve is generally kept below the maximum pressure that a compressor can handle.

So, when your compressor is close to reaching its maximum level, the pressure relief valve will purge the air from the tank.

How Do Air Compressor Pressure Relief Valves Work?

An air compressor pressure relief valve uses a simple mechanism in order to function.

  • A nozzle in the valve brings the air to a certain pressure.
  • This pressure is lower than the compressor’s maximum pressure level. When the nozzle reaches this pressure, a disc inside in the valve lifts to release the air from the tank.
  • A spring then bends if the pressure reaches the set level. So, the spring lifts up and draws the disc down.
  • Then, once the pressure returns to a lower, set level, the disc will close and prevent any further air from escaping.

2.Underpowered Extension Cord

The general consensus is that it’s bad to use an extension cord with an air compressor. This is because the United States has pretty loose regulations when it comes to how extension cords are manufactured, labeled, and sold. 

Because of this, most extension cords cannot actually carry the amount of power required to power most air compressors.

So, if you need to work further from the air compressor, its best to increase the length of the air hose rather than increasing the length of the electrical connection. 

3.Pressure Switch Problems

If your air compressor won’t shut off at around 175 PSI, it might be the result of a faulty pressure switch. Pressure relief valve damage or a malfunctioning air tank can also cause this. Follow the troubleshooting tips for your specific Bostitch, Craftsman, Dewalt, or Husky air compressor.

The pressure switch is a crucial component of an air compressor. The pressure switch is a mechanical device that uses air pressure and electricity to control the operation of an air compressor. It’s a relatively simple mechanism that closes a circuit to power the motor if the system is below its set pressure level. 

We found an excellent video on YouTube that details the process of how to replace an air compressor’s pressure switch.

 

Are All Air Compressor Pressure Switches The Same?

No. While the inner-workings of these devices are relatively the same and they may look similar on the outside, one air compressor’s pressure switch is not necessarily interchangeable with another. 

4.Broken Gauges

A broken gauge is another common problem that can prevent an air compressor from turning off. When it’s working, the pressure gauge will steadily rise until it reaches the compressor’s cut-out setting.

If the tank gauge does not rise at all, or it rises a little and then stops even though the compressor is still running, then you could have a bad gauge. Try turning the compressor off and listening for any air that may be leaking from the gauge or one of its connections.

5.Motor Problems 

If the pressure inside your tank rises but then stops before it reaches the set cut out pressure, but your compressor motor keeps running, then you more than likely have a problem with the compressor pump itself.

If this is the case for you, the next step is to remove the air inlet filter and confirm that no air is coming out of it. If air is coming out of your air compressor’s air intake, you will need to replace its intake valve.

To check for this, remove the line that runs from the pump to the tank and use your hand to prevent the air flow out of the pump while it is running. If you are able to do that, then your air compressor’s high-pressure valve is the problem.

If you have an oil-lubricated air compressor and you notice air blowing out of the oil fill tube, that means your piston seals are worn out.

Bostitch Air Compressor Won’t Shut Off

Bostitch air compressors are oil-free compressors that automatically use a timed relay pressure switch to shut off at around 150 PSI.

The most common reason a Bostitch air compressor won’t shut off is because of a faulty pressure switch piece. Many people misread the dilemma and buy a new pressure switch for $12 or more when that doesn’t solve the problem. However, sometimes an entirely new part may be necessary.

There are some easy, do-it-yourself steps that you can follow to fix the issue.

Troubleshooting

  1. Unplug and turn off everything– For any troubleshooting, make sure to cut off any power source to the air compressor that might result in electrocution.
  2. Remove the pressure switch cap– All Bostitch air compressors have a pressure switch cap with a red knob. Pull that off.
  3. *Warning*– The wires underneath can be hot, so avoid touching them bare-handed. Use gloves and only handle the metal knobs with other tools.
  4. Adjust the pressure switch– Check out the adjuster underneath the cap that reads + or – pressure. If you bump the higher limit down, you might be able to trigger your air compressor to turn off appropriately.
  5. Put the cap back on– Carefully reassemble your air compressor and turn it back on.
  6. Look for leaks or dirty filters– To rule out any other issues, look for bubbles as you turn the tank on and off, as well as check for dirt around the valves or triggers. If there are leaks or dirty filters, it can cause issues with shutting down properly.

Craftsman Air Compressor Won’t Shut Off

A Craftsman air compressor cuts out at about 175 PSI, depending on the particular model you chose. They come with large, 33-gallon tanks and oil-free motors.

The most prevalent cause of a Craftsman air compressor not shutting off is pressure relief valve (also known as a safety valve) damage. This part could be threading improperly, causing excess air to be released from the tank, or the spring inside could be worn.

A pressure relief valve is used for sensing the pressure in an air compressor. It’s intended as a last resort to shut off the compressor when the preset pressure limit has been reached (in this case, 175 PSI).

It’s essential that your pressure relief valve is working properly, so there is no over-pressurization of the air tank. If this valve is being triggered, it’s possible that the pressure switch is not being signaled to do its job.

There are a couple of ways to address this problem.

Troubleshooting

  1. Unplug and turn off everything– For any troubleshooting, make sure to cut off any power source to the air compressor that might result in electrocution.
  2. Depressurize the air tank– Remove all of the air from the tank by unscrewing the drain underneath the machine (look at the manual for its exact location). Once the hissing stops, the tank is empty.
  3. Remove the manifold cover– This will require a small screwdriver.
  4. Unscrew the pressure relief valve– This part will require a wrench for the first few turns.
  5. Check out the threads– If the threads look intact, it may just be that the knob was screwed on incorrectly. If that’s the case, re-screw it properly. Otherwise, if the threads look damaged, you may need an entirely new pressure relief valve.
  6. Look for spring damage– If the spring on your valve becomes stuck open, then it’s time to replace it for around $6.
  7. Make sure to purchase the correct piece– The Craftsman air compressor pressure relief valve is preset to release at 175 PSI. You need the correct one for your model.
  8. Install the new pressure relief valve– Screw in the new piece to the manifold first by hand, then tighten with a wrench. Make sure to follow the threads.
  9. Reassemble your air compressor– Put everything back together, plug it back in, and you should be good to go!

Dewalt Air Compressor Won’t Shut Off

The Dewalt air compressor has a cut-out setting of 200 PSI– much higher than the models mentioned above.

The most common issue that won’t allow a Dewalt air compressor to shut off is a malfunctioning gauge on the air tank. This results in a pressure misreading and may not signal the machine to kick off at 200 PSI. Often, it is a result of corrosion.

This can be incredibly dangerous if your air tank is overpressurized. The good news is you can easily replace the gauge.

Troubleshooting

  1. Unplug and turn off everything– For any troubleshooting, make sure to cut off any power source to the air compressor that might result in electrocution.
  2. Depressurize the air tank– Remove all of the air from the tank by pressing the metal piece button attached to the yellow tubing. Once the hissing stops, the tank is empty.
  3. Remove the cover– This will require a screwdriver (a ratcheting version works best).
  4. Take off the manifold– Use the same ratcheting screwdriver to undo its screws.
  5. Remove the air tank gauge– This is located in the very middle and requires a wrench for the first few turns.
  6. Install the new air tank gauge– Screw the new piece into place, finishing with a wrench.
  7. Reassemble your air compressor– Put everything back together, plug it back in, and it’s fixed!

Husky Air Compressor Won’t Shut Off

Husky air compressors operate with oil-free motors and usually cut out at around 175 PSI.

If your Husky air compressor won’t shut off, likely the pressure switch is to blame. Like in the Bostitch models, if the pressure switch is faulty, your air compressor will automatically shut off when it’s supposed to. It is typically triggered when the maximum PSI is reached.

We talked about adjusting the pressure switch settings above; let’s now discuss replacing the part.

Troubleshooting

  1. Unplug and turn off everything– For any troubleshooting, make sure to cut off any power source to the air compressor that might result in electrocution.
  2. Depressurize the air tank– Remove all of the air from the metal drain. Once the hissing stops, the tank is empty.
  3. Remove the cover– This will require a screwdriver.
  4. Take off the manifold– Use the same screwdriver to undo its screws.
  5. Remove the wiring– Undo the wiring from the old pressure switch (beware these can be hot- wear gloves), and take off the pressure gauge for manipulation purposes.

Install the new pressure switch– This requires some re-wiring. Take a look at this short video to help with the visual process.

Is It Dangerous If My Air Compressor Will Not Shut Off?

Yes. If your compressor won’t shut off, you are on the edge of disaster. While there are several mechanisms in place to prevent a high pressure tank rupture, if your air compressor will not turn off, you are depending on one or two small devices to prevent an explosion.

Why Is My Air Compressor Continuously Running?

There are many possible reasons why your air compressor continually runs. It could be something simple like a bad seal, or something more complicated and expensive like a failed motor or bad intake valves. 

An air compressor continuously running can cause premature motor failure. This is especially important in reciprocating compressors, as they rarely have a 100% duty cycle and need some amount of cool-down time. 

At What Pressure Should An Air Compressor Shut Off?

That depends on what you set it at, but the general rule is that the difference in pressure must be at least 14.7 PSI or 1 BAR. If you set the pressure level any lower than this, it will cause the compressor motor to turn off and on again rapidly, which is not good for the motor. 

Conclusion

As it turns out, there are several different reasons why an air compressor will not shut off. An air compressor not shutting off when it’s supposed to can be a dangerous situation. In the worst case scenario, something could explode. 

The chances of that happening are rare, but if your air compressor wont turn off, it will definitely cause your compressor to wear out prematurely.

Some of the most common reasons for an air compressor not turning off are the pressure switch failing or a leak somewhere in a line or the tank itself. You could also have a faulty O-ring, and this can also happen if you are using an under-rated extension cord. An air compressor not turning off could also be a sign of bad valves inside the compressor motor.