How Does an Air Compressor Switch Work

How Does an Air Compressor Switch Work?

Spread the love

You probably know what an air compressor is, but do you know what the switch is? What is this thing and how does an air compressor switch work?

What is an Air Compressor Switch?

The air compressor switch is a mechanical component that is present in air compressors. The function of the switch is to measure how much pressure is inside of the air tank, and then to shut of the compressor’s motor, to stop it from accumulating more air in the air tank, past a certain point. 

This is something which will help your compressor maintain a proper level of air pressure while you work with them.

It is a vital component of any air compressor, because if the air switch does not work, the compressor will not turn off once the air tank has reached maximum capacity, and it could therefore explode, crack, or suffer from severe damage. This air compressor switch is also necessary to turn the motor back on to continue pressurizing air once the tank has fallen below a certain pressure level.

How Does an Air Compressor Switch Work 2

How Does the Air Compressor Switch Work?

The air compressor pressure switches from one level to another using air lines which monitor the pressurized air as it moves to and from the air tank in the compressor. All of the pressure switches have an element which reacts when a certain amount of pressure is applied to it. The most common device found in air compressors which performs this function is the diaphragm, which physically compresses when exposed to this pressurized air.

When you turn on your air compressor, it will keep filling up the tank with air until it has built up enough backwards pressure to change the shape of this diaphragm, and when this deforms it will cause the pressure switch to move. Once this air compressor switch diaphragm has reached a certain level of deformation due to the air pressure, it will move enough so that it causes a break in the circuitry. This break in the circuitry then shuts off the motor of the air compressor and stops more pressure from building up or air from being pumped into the tank.

If the air pressure remains constant at that specific volume, the diaphragm on the switch will remain deformed. When the air pressure in the tank drops, or in other words, if you either use the air pressure to fill up a tire or power a tool, this diaphragm will then return to its original state.

At the same time, there is also another internal part inside of the switch which then deforms in the same manner when the pressure drops. This then causes the switch to close the circuit and then restart the motor, thus beginning the pressurization process once again. This will continue happening as long as you are using machinery that uses compressed air, such as a nail gun.

Checking the Air Compressor Switch 

If you are having issues with the air compressor switch, you can use an ohm measuring device and a separate air source to see whether or not it is working properly. Let’s talk about how to check your air compressor switch in an easy to grasp step by step manner.

How Does an Air Compressor Switch Work 3
  1. Unplug the air compressor. Never do this testing with it plugged in.
  2. Then, unscrew and remove the housing of the air compressor.
  3. Locate the terminal block and the pressure switch so you can disconnect the wires running between the two. These wires are usually blue or brown.
  4. Make sure to leave the black and white wires connected, as they power the switch and are difficult to replace or repair if you happen to disconnect them.
  5. Now that you have found the valve, apply air to the pressure switch. You have to use an air source that creates more air pressure than the level at which the switch is currently set.
  6. After the air pressure has been applied, use the leads of your ohm meter on the loose wires.
  7. If the ohm meter reads “0,” it means the switch is closed due to the pressure, and the switch is in working order.
  8. If your ohm meter gives you a reading other than that, there may be an issue.
  9. You can turn the set-point-screw counterclockwise to adjust the switch’s set point. Keep applying pressure as you do this, and once the ohm meter reads “0,” then all is good. If you cannot get it to read “0,” you may have to replace or repair the switch.


There you have it; the air compressor switch is a vital component in these machines and needs to be in good working order.

Click Here to Leave a Comment Below

Leave a Reply: