A Quick Guide to Air Compressor Pressure Switch Adjustment

A pressure switch of an air compressor helps to start and stop the compressor automatically. It does that by letting you adjust the cut in and cut out pressure.

In this guide, you can learn about air compressor pressure switch adjustment in the easiest way possible. But first you need to know a little about cut in and cut out pressure so that you know how pressure switch works.

The cut in pressure is the pressure you set for the compressor to start running and the cut out pressure is set for the compressor to stop.

The mathematical difference between these two pressures is called the pressure band. For adjusting the pressure switch of a compressor, these two pressures are to be set.

How to Adjust Air Compressor Pressure Switch

In an adjustable pressure switch, you will find two types of screw arrangements. One is for fixed range and the other one is for an adjustable range. This range is the difference of cut out and cut in pressure or the pressure band as I have said earlier.

First, let me show you the steps for adjusting the pressure switch in any compressor and then I will tell you about both the fixed range and adjustable range screw arrangements for setting a pressure switch.

  • First of all, disconnect your compressor from any kind of power source and take off the cover of the pressure switch.
  • Now you have to set the cut in pressure first. The screw that is closer to the motor is usually the cut in screw. Set the pressure accordingly.
  • Next, you have to set the cut out pressure (for adjustable range screw arrangement only) as your requirement.
  • For both cut in and cut out pressure, increase the pressure level by turning the screw clockwise. To decrease the pressure level, simply turn the screw anti-clockwise.
  • Connect the compressor to the power source again, and drain all air out of the tank. Then turn it on to test if it runs in cut in pressure and stops in cut out pressure.
  • If it’s running accordingly, you are all set. If not, then set the pressure switch again and make sure to drain the air out of the tank properly.
A Typical Diagram of a Pressure Switch
Air Compressor Pressure Switch Diagram

Here is a little brief on the fixed range and adjustable range screw arrangements for compressor switches.

Fixed Range Screw Arrangement for Pressure Switch

In the fixed range switch, there will only be one screw for adjusting air compressor pressure switch. Here, when you set the cut in pressure, the cut out pressure will automatically be set. For example, if you set the cut in pressure to 90 psi, and if the pressure band is 40 psi, then the cut out pressure will automatically be set to (90+40)=130 psi.

Adjustable Range Screw Arrangement for Pressure Switch

In the adjustable air compressor pressure switch setting, you can set the pressure level of both cut out and cut in pressure by regulating two different screws. Usually, of the two screws, the left one (or the one which is closer to the motor) is for the cut in pressure and the right one is for the cut out pressure.

Why You Need to Adjust Air Compressor Pressure Switch

It is not always necessary to adjust air compressor pressure switch as the compressor you have will give you a default adjustment which is best for the compressor. Here are the reasons why you need to adjust the pressure:

When You Replace the Pressure Switch

In case you have to replace the pressure switch, you will need to adjust the pressure level of the new switch.

The new settings of the pressure switch should be similar to the old one you had. Otherwise, your compressor will get damaged for unbalanced pressure adjustment.

To Save Money on Electricity Bill

Another reason to adjust the pressure is to save your electricity bills. It’s simple. The higher the pressure you give to your compressor the more energy it will take to run.

In that case, providing more pressure than your requirement, will simply waste electricity and increase your bill. So, you should just set the pressure to a level you need and not more than that.

Frequently Asked Questions

How many types of pressure switches are there?

There are two types of pressure switches, one is adjustable and the other one is non-adjustable.

  • The non-adjustable pressure switches have fixed magnitude and you cannot adjust the pressure of this switch.
  • The adjustable pressure switches are the one where you can set the pressure according to your need.

You can find out if the pressure switch is adjustable or not by looking inside of the pressure switch. Remove the cover and inside you will see the pressure screw.

If the screw is sealed that means you cannot adjust the pressure with that switch. On the other hand, if the screw is free then you can adjust the pressure.

How do I know if my pressure switch is bad?

You will know you have a bad pressure switch by a few signs. For example:

  • If your compressor doesn’t start even after reaching the cut in pressure.
  • When the compressor is not stopping at cut out pressure.
  • If the safety relief valve keeps opening unnecessarily.

What happens if pressure switch goes bad?

If the pressure switch goes bad then your compressor won’t run properly. It won’t start as you want and won’t stop automatically after reaching the cut out pressure.

When this happens, the safety valve will frequently open. You won’t be able to work properly with the compressor as it will suddenly start and stop.

How long do pressure switches last?

An average quality pressure switch can last from 5 to 7 years whereas a high-quality pressure switch will support you for more than 10 years without any problem.

Some Final Tips

You don’t have to work on air compressor pressure switch adjustment unless it’s absolutely necessary. As long as the default switch is working, you don’t have to replace the switch.

But, in case if you do replace the switch, you should know how to set pressure switch and make sure to keep the pressure level the same as the original one. Or, your compressor will get damaged because of the unusual pressure adjustment.

Finally, keep the pressure band higher (20 psi or more) so that your compressor doesn’t start and stop rapidly as it can also damage the compressor.

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