how does air compressor pressure switch works

Have you ever wondered how your air compressor pressure switch works? It’s a pretty simple device, but understanding how it controls the flow of air to your compressor can be helpful when troubleshooting problems. 

Air compressor pressure switch helps maintain the desired pressure level and ensures that the compressor does not operate beyond its safe limit.

The air compressor pressure switch is used to measure the amount of pressure needed inside your tank. If you set it up correctly, the pressure switch will shut off the air supply when the tank reaches a certain pressure.

Have we done here? It was a quick overview. If you’re looking for more in-depth information about how does air compressor pressure switch works and many more questions related to the pressure switch, then let’s get started.

What is a pressure switch?

In simple words: pressure switch is a safety device that automatically switches airflow on or off depending on the level of pressure in your tank. This process prevents the air compressor from operating beyond its safe limit. 

It is important to set up pressure switch correctly to prevent over-pressurization of your air tanks, which could lead to an explosion. So always make sure this part works fine by monitoring its functionality with regular inspections or repairs when needed.

How does air compressor pressure switch works?

Every air compressor model has different operating parameters set by what it needs for efficiency or safety purposes, but the basic functioning of an air pressure switch is simple to understand.

The working of a pressure switch is based on a simple pneumatic concept. When the air tank reaches a certain pressure, it pushes a piston that makes contact with an electrical switch, thus turning on or off the compressor.

The switch is linked to a safety valve, which will open if over-pressurization occurs. The pressure switch is specially built to react when there is increased pressure. This is usually done with the help of a diaphragm.

The air compressor pressure switch has cut–in and cut–out settings to prevent overpressure. The cut-in pressure setting refers to the minimum pressure required that tells the compressor to start, while the cut-out shutdowns the system when it reaches a certain pressure level. These points are set by adjusting the tension of adjustment springs.

Note: It is always better to select a pressure switch with adjustable cut-in and cut-out pressures. This way, you can set it according to your air tank’s maximum safe pressure level.

How can I adjust cut-in and out pressure?

The tension applied to adjustment springs sets the cut-in and out pressures. Set the cut-in and cut-out points to the midpoint of the compressor for safe working pressure.

If the pressure switch is set at the wrong point, then the compressor can operate either below or above its safe limits and be subjected to serious damage.

If you set these points too high, it could lead to the compressor not shutting down in time, resulting in an explosion. On the other hand, if you set these points too low, the compressor will work overtime and overheat.

It is generally recommended to set the cut-out pressure at least 10 to 20 psi (pounds per square inch) higher than the cut-in pressure.

Component of air compressor pressure switch

There are a variety of components that make up an air pressure switch. These components can be differ depending on the type and model, but they will generally include:

Terminal Function

Terminals are responsible for transferring electrical current into the switch. The two main terminals in the pressure switch are wired to the power cord used for the power supply and compressor.

When the electrical current reaches the pressure switch, it activates a magnet. This, in turn, moves the metal lever over to open or close the circuit automatically.


Contacts are responsible for completing or breaking an electrical current per pressure levels inside your tank. The two main contacts included in the pressure switch are connected to both terminals. These tiny metal strips remain connected until they come between the magnet and metal lever, making them open or close the circuit.


The diaphragm is responsible for sensing pressure levels inside your tank. All pressure switches come with a diaphragm made of rubber or plastic. As the pressure inside your tank increases, it pinches the diaphragm and closes the circuit.

Pressure switch relief valve

Pressure switches come with a pressure switch relief valve responsible for releasing excess pressure inside your tank. If your tank’s pressure exceeds the maximum value, then the excess gas will escape through this relief valve. If the pressure switch relief didn’t work properly it cause the compressor to overheat and trip the breaker.

Adjustment springs

Adjustment springs are responsible for setting the desired pressure level inside your tank. The pressure of your air compressor will depend on how you adjust the cut-in and out points with a spring.

When you tighten the tension, more pressure needs to come from inside before it makes contact between two sides; but if there is less force on one side (or both), they will move apart easily without any resistance.

Auto/off lever

A pressure switch comes with an auto/off lever responsible for manually increasing or decreasing the amount of air required inside your tank.

Every pressure switch model comes with its own unique pressure range for switching on and off the compressor, which depends on the application it is used for.

What Does Pressure Switch Look Like? 

A pressure switch is generally a flat piece of metal with two small bars attached to the top and bottom.

These bars are responsible for switching the compressor on and off based on the pressure inside your tank. They can be just a small flat piece of metal or made of rubber or plastic.

You can see the black box on the top, it contains all of the functional elements, such as how to adjust cut-out and cut-in pressure levels. The handle with the red knob (bottom front) is responsible for turning the compressor on/off.

On the (right side), you can only see the top of the tank air gauge. The gauge shows not only the tank’s internal pressure but also displays the cut-out pressure level when the compressor is turned off.

Maintain your pressure switch regularly

If you want to use your pressure switch for a long period without any difficulties, you must make regular maintenance a priority. 

Always keep the tank clean at all times, mineral dirt and water sports on the switch can reduce its performance.

I highly recommend you to check for cracks, if you see any leak, crack on your pressure switch, replace it immediately. Because your air compressor pressure switch holds the air inside your tank, making them very sensitive to impact. So make sure you’re not dropping, bumping, or pushing it too hard.

If your pressure switch stops working or does not function properly, you should consider getting a replacement. 

Check Leakage And Repair Pressure Switch

When checking your air compressor pressure switch, it’s important to double-check for any leaks. I’ve noticed that the switch diaphragm cracks over time, which prevents it from maintaining the pressure inside the tank correctly. When you notice any cracks in your diaphragm, you should replace them immediately.

To find the leaks, all you need to do is attach your compressor to an air tank, turn it on and leave the valves open. This should produce pressure inside your tank to check for all leaks.

If there is any leakage, it will manifest itself in the form of air (or water) flowing out of the tank. If you want to repair your compressor pressure switch, I suggest contacting a professional. 

Some Guidelines to take note of when using air compressor pressure switch:

1. Never attempt to use your pressure switch for any application other than its designated purpose because different applications require different settings on the switch.

2. Always allow your pressure switch to complete its process before switching on the compressor, which will avoid any damage due to electrical sparking or excess pressure.

3. Don’t try to repair it yourself. If you don’t know what you are doing, take your unit to a certified professional technician.

4. Make sure the switch is always located in an accessible position so that it can be maintained properly.

5. Never place any heavy objects on the cord of the pressure switch, which may damage or short circuit your switch.

What are the different types of air compressor pressure switch?

There are two types of switches used in the market:

Float Switches

Float switch is one of the most popular pressure switch used in air compressors. A float-activated switch is a simple device What are the different types of air compressor pressure switch?when the air tank hits its desired pressure.

It contains a small float inside, which moves with the pressure and activates a small contactor that switches the air compressor on or off. When the switch gets activated, it also activates a safety valve to prevent your tank from over-pressurization.

Timer Switches

This type of switch contains a timing mechanism that turns the compressor on and off at specific intervals. Timer switches allow you to save on energy, as the compressor restarts after a few minutes when the pressure drops. It enables you to run your air compressor for a brief time.

Timer switches are not that common type used by air compressor manufacturers. It’s been replaced by float switches due to their simplicity and operational safety.

When does the air compressor pressure switch turn off and on?

The piston rod slides up and down inside the cylinder when the compressor is in use. When the tank pressure is below the cut-in pressure setting, the top of the piston rod is exposed to atmospheric air pressure, so it slides down.

When tank pressure reaches the cut-in pressure setting, the piston starts to lift until it reaches the full stroke.

The air compressor switches off when tank pressure exceeds the cut-out pressure setting. This means that the air tank will remain pressurized only as long as the user operates the compressor.

Once the user stops the compressor, it shuts off and restarts only when the cut-in pressure setting is reached.

Final Words

That’s all about how does air compressor pressure switch works. I hope that this informative article has helped you. I again recommend you always hire a professional to repair your pressure switch (if you don’t know how to repair it). And regularly maintain your air compressor pressure switch to ensure it runs smoothly.

Thank you for reading the article, and if you have any questions regarding this article, don’t hesitate to contact us.

By Matthew