How To Replace AC Low Pressure Switch: Detailed Guide You Need To Follow

We spend a lot of our time in the car. But staying in your car without AC in this hot climate can be like living in a hell. But how many of us know how to take proper care and maintenance of the AC in our car? How many of you know how to replace AC low pressure switch?


Part of being a responsible car owner is to know how to take care of small repair and maintenance work around your house. This includes small repairs to the AC as well. Getting a trusty mechanic is not an easy task anymore. They cost too much and are rarely free at the times we need them the most.

Learning how to do minor repairs in your car can help you save both money and time. It is also a good way to spend time with your machine. Here we will be talking how to repair the low-pressure switch in your air conditioner.

How To Know If Your AC Low-Pressure Switch Needs Replacing Or Not?

Before we talk about how to change the AC low-pressure switch, we have to know about the symptoms of a faulty AC pressure switch.

The AC pressure switch is a device mounted on the high and low side of the AC. It monitors the pressure of the refrigerant on both sides of the system. There is a separate switch for the high side and the low side. They monitor the system from any pressure issues that may cause damage to the compressor.

When the pressure of the system goes below 25 psi, they shut off the system momentarily. This prevents the air conditioning system from freezing up, particularly in colder climates. So, making sure that your AC pressure switch is working is essential for the long life of the air conditioner.

When the AC pressure switch of your car becomes faulty or malfunctions, there are many issues with the car’s air conditioning system. It includes the AC cutting on and off without cause, the inability to cool your car and so on.

These symptoms mean that your AC pressure switch needs repair or replacing. When your car’s air conditioning system begins to showcase these symptoms, it might be the time to replace your AC’s pressure switch.

Tools For The Tutorial

Before you can start with the replacing of the air conditioning system’s pressure switch, you will need some tools for the job. But don’t worry, you can find most of them lying around in your garage or tool box or come with the system. You will need:

  • Air conditioning gauge set
  • Air conditioner recovery machine
  • Refrigerant
  • Vacuum pump
  • New pressure switch
  • Rubber O ring

This pump is used for creating vacuum inside the machine by removing gas molecules from a sealed container.

If you don’t have any of the above-mentioned equipment, they can easily be bought from the local hardware store and can come in handy in the future. Any money you spend on buying the equipment can help you save more when it comes to repair and maintenance cost.

Let’s Get Started!


Removing The Refrigerant In The Air Conditioning System

To replace the AC pressure switch, you have to remove the refrigerant in the system. It is advised not to release the refrigerant into the open as it can contribute to the greenhouse effect. Connect the recovery machine’s larger hose to the low-pressure port of the system and the smaller hose to the high-pressure port.

Turn on the machine and remove the entire refrigerant. There will be a gauge that shows the amount of refrigerant removed.


Replace The Pressure Switch

The position of the air conditioner pressure switch changes depending on the model. So consult your manual to find it. Remove the switch by unscrewing it from its position. You will also have to remove the rubber O-ring and replace it with a newer one. They generally come with the pressure switch. You should make sure that the pressure switch you are using is the correct one for your system.


Removing The Moisture From The System

You will have to get rid of all the moisture in the air condition system before you can fill it with the refrigerant. Take the air condition gauge set and connect it to the pressure port mentioned in the first step. Now connect the gauge set with a vacuum pump and switch it on, along with the service valves in the gauge set.

You should let it run for nearly one hour. This will ensure that all the moisture in the air conditioning system is properly removed. If any moisture remains in the system when you fill the refrigerant, it causes the air conditioning system to malfunction.


Reapplying The Refrigerant

Now that the moisture from the air conditioning system is completely removed, it is the time to refill the refrigerant. Close the service valve and remove the vacuum set. Attach the can tap which comes with the gauge set and connect the can of refrigerant to it.

To refill the system with refrigerant, open the service valve of the gauge set and the can of refrigerant. You will have to keep replacing it till the refrigerant is fully replaced. To know how much amount of refrigerant is needed for your system, refer to your manual.



Now that you have completed the replacing of the AC pressure switch, it is the time to check if it is properly installed and working without any fault. Remove all the hoses and close all the valves of the system. Turn off your car for 10 minutes. After 10 minutes, start your engine and run your air conditioner at full capacity.

Check whether the old symptoms are still there. If the air conditioner is back to proper and consistent cooling, it means that you have successfully replaced your AC pressure switch.


I hope that the above article would have helped you in learning how to replace your AC pressure switch. Knowing such small repair and maintenance work can help us save our money and time.

Issues with the car’s AC system are common and need to be taken care of properly. So, learning how to take care of your car can be of great benefit. It is always good to be self-sufficient and capable of doing such repair and maintenance work without the help of others.

If you have found what you were looking for, then kindly share the article with others so that they can also take benefit of the knowledge. Also, if you have any further queries or comments, feel free to contact us through the comments.

Abigail Jones

Hi, I'm Abigail. I like spending time tearing my house apart and putting it together back again. Join me on home improvement tutorials, tips on my blog.

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