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How to Replace AC Low-Pressure Switch: A Complete Guide

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If you are a car owner, you should know how to replace AC low-pressure switch by yourself. This skill is necessary to ensure that you won't encounter any problems while you are on the road.

But what exactly is an AC low-pressure switch?

Specifically, the air compressor pressure switch is the component in the engine of your car that somehow controls the air conditioning itself. It can either cut or provide the power to the system, depending on the current pressure that it has. For instance, if the strength of the air compressor is 25 PSI or below, the switch will automatically curtail the power that it provides. As a result, the air conditioning of your car stops temporarily.

Of course, this mechanism is fundamental. Without this, your entire air conditioning might freeze up because of the unregulated temperature. It could result in significant damages in the car's engine, too. If the AC low-pressure switch is dysfunctional already, you need to replace it immediately. Otherwise, further issues could arise.

But do you know to do it by yourself? If not, then pay attention to this comprehensive tutorial that I am going to give you. Get all the necessary tools needed so that you can practice right away.

How to Replace AC Low-Pressure Switch

How to Replace AC

Things you need:

  • Air conditioning gauge set
  • Air conditioning recovery device
  • Brand-new pressure switch
  • Vacuum pump
  • Refrigerant

Step 1: Taking Out the Refrigerant

1. The first thing that you need to do is to remove the refrigerant from the car first. You cannot replace the air compressor switch if the coolant is still working.

Always remember that the refrigerant is a major contributor of greenhouse gases. Therefore, exposing them to the air is an act of pollution of already.

2. To remove the refrigerant, you need to affix the hoses of the recovery machine to the ports of the air conditioning. You can spot two ports here (one is the low-pressure port, and the other one is the high-pressure port). Usually, the larger one is the low-pressure port. On the other hand, you can locate the high-pressure port by trailing the small hose that you can find on the back portion of the car's compressor.

Taking Out the Refrigerant

3. Once done, start the engine of your car. Doing this will automatically expel the refrigerant. Your car should have a gauge or monitor that will tell you the amount of refrigerant left.

Step 2: Replacing the Switch

The placement of the AC switch is not always uniform. The location varies from different car models and manufacturers. Therefore, it is proper that you check the switch of the positioning with the help of the car's manual. After you spotted the switch, you can start removing it by taking out the screws that pin it. Use the appropriate type of screwdriver in removing the bolts.

Replacing the Switch

Also, make sure that you also remove the O-ring in where the switch is connected. Typically, AC switch replacements always come with spare O-rings. When choosing a replacement switch, make sure that you look for the same spec as the one that is in your car. Compatibility issues could arise if you don't use an appropriate AC switch.


  • Take note that the AC system of your car doesn't need to be removed if you want to change the AC switch. That is thanks to the presence of a Schrader valve that gets integrated to the mount of the switch. If you are quite unsure about this, you should just refer to the car's manual for further information. Alternatively, you could also talk with professional technicians so that they can see the setup of your vehicle.
  • Before you remove the AC low-pressure switch, you have to disconnect the negative battery cable and the electrical connector of the switch first. Just install them back once you have installed the new AC switch.

Step 3: Removing the Moisture

Removing the Moisture
  1. It is not enough that you just simply remove the AC low-pressure switch alone. You should also expel the remaining moisture that you can find in your air conditioning system. To do this, use the air conditioning gauge device and attach their hoses to the pressures ports that I mentioned in the first step.
  2. Next, connect a vacuum pump to the gauge device and crank it up. By doing this, the moisture in the air conditioning system of your car will get removed. It should take around an hour or two before all the moisture are sniffed out.

Step 4: Putting back the Refrigerant

  1. Once you are finished removing the moisture, disconnect the vacuum pump that is attached to the gauge set. Don't forget on seal the service valves of the gauge set, too. Next, find the can tap of the gauge set and install it to the latter. You need to do this so that you can connect the container of refrigerant to the gauge set.
  2. By this time, you can already open back the valves for the refilling process to start. Just continue filling the refrigerant until the car system gets supplemented adequately.
  3. Remove all the devices and machines that you attached to the car's system. Next, shut down its engine and let it be idle for around 10 to 15 minutes. After this period, crank the engine again and activate the air conditioning to its fullest capacity. Assess if the switch that you installed works.


Once more, let me remind you that it is necessary that you know how to replace AC low-pressure switch on your vehicle. By doing this, you can save your car from heating up consistently. Of course, a broken air conditioning can cause insurgence of other engine problems. Therefore, you have to do this from time to time.

Fortunately, this is a maintenance procedure that you can do alone. You don't need the help of professional technicians to handle this job for you. If you got the right tools, you could remove and replace the AC switch right away!

Do you have any questions? Just feel free to ask in the comment section below!





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