How To Bypass Pressure Switch On Air Compressor

How To Bypass Pressure Switch On Air Compressor

If your air compressor has been acting up recently then the problem could be due to the pressure switch. I’ve read stories online of people who have purchased air compressors online for a ridiculously low price, and the reason is that they just won’t turn on.

The answer is to cut out the middle man, which in this case is the pressure switch. But before you do anything, you’ll need to know how to bypass the pressure switch on your air compressor.

The solution is to put a jumper wire across the contacts on the pressure switch. However, there are some things that you will need to monitor otherwise you run the risk of burning out the motor.

In this guide, I’ll be telling you everything you need to know to bypass that pressure switch and solve any problems to get your air compressor working as expected once again.

What Does A Pressure Switch On An Air Compressor Do?

Before we start talking about how to bypass the pressure switch on your air compressor, we need to understand what it does. A pressure switch uses air pressure as a way of controlling an electrical air compressor.

These mechanical devices ensure that power is delivered to the motor by completing the circuit. But it can only do this if the pressure of the entire system is below a specific level. Most air compressor’s pressure switches will be fitted with a relief valve that reduces pressure when it is needed. As a result, the air compressor will start more easily.

There are several different types of pressure switches and each air compressor may be fitted with something slightly different. However, all of these designs work in a very similar manner.

When you connect your air compressor to power and move the lever into the auto position, this forces internal electrical contacts to come together which completes the circuit. At the same time, your air compressor’s motor starts up and pressure within the compressor starts building up.

When the desired pressure is achieved, there is a diaphragm within the pressure switch that pushes against another mechanism which in turn, breaks the contact between the electrical components and stops the motor.

While this is happening, the pressure relief valve will open and reduce any pressure between the check valve and pump. When you use your air compressor, the tank pressure will drop. When this happens, the motor automatically fires up again and so the cycle continues.

How To Bypass Pressure Switch On Air Compressor

If you are having problems with your air compressor getting started or staying running then it is possible to bypass the pressure switch. This will ensure that the motor doesn’t turn off until you want it to. But there are risks involved with this.

You will need a jumper wire which you will put across the contacts of your pressure switch. This will prevent it from stopping but you absolutely must make sure that the safety valve is in good working order and running as expected.

It’s also important to make sure that this valve has the capacity to release the entire compressor. If it doesn’t then there is a very significant chance that the air compressor could explode. And this won’t be a minor event, this is something that could be potentially fatal. So it’s worth weighing up whether it’s worth the risk or whether you should simply repair or replace your compressor.

You’ll normally find that doing this will quickly cause the air compressor to overheat which will result in the motor burning out. The only time that this won’t be an issue is if you are using an industrial air compressor. But how many of us have one of these in our workshop at home?

Do I Need A New Pressure Switch?

If you are having problems with your air compressor and have decided that bypassing your pressure switch isn’t worth the hassle then it now comes down to deciding what, if anything, needs replacing. You’ll easily be able to tell if your pressure switch is what is causing the problem by considering the following things.

Air Compressor Stops Before It Reaches The Cut Out Pressure

Let’s assume that your air compressor should be cutting out at 120psi but at the moment, you’re finding that it stops when it reaches 95psi. This is a pretty obvious indication that there is something wrong with the pressure switch.

The best way to determine this for sure is by checking the switch with a multimeter. This will tell you whether there is still power running through the pressure switch and to the motor at the point that the compressor cuts out.

Your pressure switch has two sides. One of these is the motor side, sometimes called the load side, while the other is the power supply side. Power needs to be flowing between these two sides and you need to know whether this is the case when your air compressor cuts out. If it is not then the pressure switch will trip prematurely.

Air Compressor Is Not Starting At All

There’s nothing quite as frustrating as having a tool that just won’t turn on. In this case, your air compressor tank pressure will run-up to the point of cutting out and your air compressor has stopped. Alternatively, it could be that the pressure has been drained when the compressor was last used. If you then plug it in, you’ll likely notice that nothing happens.

In this situation, the problem might not be related to the pressure switch but there could be problems so it is worth checking out. It’s likely to be the pressure switch if your tank pressure is totally empty or is at the lower end of the cut setting. You can check this using your multimeter.

In the event that you discover the power is still going through the pressure switch to the motor, it is likely that that switch has tripped but is still working.

Air Compressor Turns On And Off

Sometimes, you may find that you are using air from the tank and your air compressor starts up again in order to build up pressure again. That’s how it is meant to work but in some cases, after the tank is filled a little, the compressor turns off for some time before restarting. It all feels a little sporadic, right?

Once again, you’re going to need to see if this is a problem with the pressure switch using a multimeter. It’s important to check this before the tank has reached the cut out setting while the compressor has stopped. This will tell you if the switch has turned off and prevent any further power from flowing to the motor. If power is still flowing then it is unlikely to be an issue with the pressure switch.

How To Repair An Air Compressor Pressure Switch

So you have determined that your pesky pressure switch is the culprit in why your air compressor isn’t doing what it is supposed to do. The natural thing to want to do is to try and repair it. However, taking apart a pressure switch and trying to fix it isn’t a job for a layman. You’d normally need a pro to come out and take a look at the switch, performing any necessary repairs.

What’s more, if you are using a low-end pressure switch, the parts in these cannot be serviced by the user. Moreover, it’s often much less time consuming and more affordable to simply replace the switch entirely.


If you have an air compressor, you will know how versatile these tools are and for this reason, you probably get a lot of use out of yours. So, there’s nothing more annoying than an air compressor that won’t function correctly and one of the most common problems is the pressure switch.

It is possible to bypass this switch and prevent your compressor from switching off or cutting out prematurely. However, there are some pretty serious risks involved in doing this that could damage your compressor, not to mention the risk it poses to your safety.

It’s much better to suss out the problem and, where necessary, replace the pressure switch. Doing this should solve all your problems and your air compressor will be ready to go once again.

How To Bypass Pressure Switch On Air Compressor

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