AC Low Pressure Switch Location and How to Replace it - A New Way Forward | Automotive and Home Advice & Review (2024)

The first and the most important thing that you need to know before we get to the location of the AC low-pressure switch is that what it really is and what does it do.

What is an AC low-pressure switch?

An AC pressure switch is a switch that is used for safety. It is mounted on both the low and the high sides of the Air conditioning system and is there to measure the pressure of the refrigerant that is used in the system on both sides of the system.

As I have already mentioned, there are two switches mounted on each side; the high and the low. The one on the high side is called the high-pressure switch, and the one on the low side is called the low-pressure switch.

What does an AC low-pressure switch do, and why is it important?

An AC low-pressure switch is to measure the pressure faults in the system and to identify them timely because if the pressure faults are not timely corrected, it may lead to causing damage to the compressor.

When the pressure is too low, which can be measured by the AC low-pressure switch, then the compressor is at risk because it is running at low oils and similarly if the pressure is high, which is measured by the AC high-pressure switch then the compressor may be running too high and can lead to overheating and burning.

In either case, when the pressure is too high or too low, the respective AC pressure switch switches the AC system off, and this way saves the compressor from getting damaged.

As you can see, AC pressure switches come in pretty handy when it comes to saving and expanding the lifespan of the compressor. Therefore, it is important to replace either of the switches if they are causing the problem.

For this, you will need to know how to identify whether the switch is causing problems and once you have identified it, how to fix it or replace it, for which you will need to know its exact location on the Air conditioning system.

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Where is the AC low-pressure switch located on the Air Conditioning System:

There are two pressure switches located on each Air Conditioning system. One is to monitor the high pressure, and the other is to monitor the low pressure.

The location of these switches, vary from car to car and their different models and also which of the switch is at fault and you are trying to replace.

Both of these sensors are mostly located at either the engine bay or either under the front or on the Air Conditioning condenser. In this article, we will only be going through the AC low-pressure switch’s location.

The AC low-pressure sensor is located at the line that runs from the compressor component of the system through the evaporator or the firewall of the system, up to the condenser on the low-pressure side of the air conditioning system.

If you are trying to replace the sensor, know that the R 134-a hoses used for recharging will only fit through the low side service port on all the R1 to 34a cars and other vehicles and on the R-12 cars or vehicles that have been converted to R-134a.

Now, if you don’t know where the air conditioning system’s condenser is located, then it is a radiator that is positioned between the grille of the car and the engine cooling radiator. There you can locate the AC low-pressure switch.

How to know that your AC low-pressure switch is not working properly?

There are several ways of identifying when a low-pressure AC switch is not working. Here we have mentioned the three most common ways that are easy to observe so that you may know that your AC low-pressure switch needs to be replaced.

Air Conditioning system turning on and off rapidly?

As we discussed earlier, an AC low-pressure switch switches the air conditioning system off when the pressure is too low. So if your AC system is being turned off every time you try to turn it on, it may be that the AC low-pressure switch is not working properly.

Though the same happens when the pressure is too high, which is when the AC high-pressure switch turns the system off, so it is important to make sure which of the two switches, the AC low-pressure switch or the AC high-pressure switch needs to be replaced.

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Car not being cooled properly:

As we told you earlier, it may be that either of the two switches, the low-pressure switch or the high-pressure switch isn’t working, when the system is being turned off rapidly after being turned on. Therefore, it is also important to be able to identify which of the two switches is at fault.

If the AC low-pressure switch isn’t working properly, then it means that there is not enough oil in the system, and the compressor is working at low pressure, this leads to the AC system not being able enough to be able to cool the car properly. In such a case, you should replace the AC low-pressure system.

On the other hand, if it’s the high-pressure switch that is at fault, then it means that the compressor is working at high pressure, and it may lead to overheating of the system. In such a case, you may observe overheating and will be able to identify that the fault is in the high-pressure switch.

Compressor not working:

Now, as we discussed earlier, the AC low-pressure switch turns the system off if it senses that the pressure is too low.

The compressor is the component of the air conditioning system that is responsible for making the refrigerant flow through the system, which causes the car to cool, and if the system is entirely shut, then the compressor won’t be able to turn on at all.

Also, we know that when the pressure is too low, the compressor won’t be able to turn on while, on the other hand, in case of the pressure being too high, the compressor might turn on but be overheated. Therefore, this is also a great indication that the AC low-pressure switch isn’t working.

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How to replace the AC low-pressure switch if it is not working properly:

Now once you have successfully identified that the AC low-pressure switch is at fault, it is important to replace it as soon as possible because otherwise, it might damage your compressor.

Step 1: You are already down one step, as you also know where to locate the AC low-pressure switch.

he replacement of the switch itself is pretty easy, but in some cases depending upon the car and the position where the AC low-pressure switch is located, the replacement might become slightly harder as the point might be too cramped, and it can get difficult to fit tools through it.

Step 2: Once you have located the sensors look at the size of the pipes. The smaller pipes mostly lead to the high-pressure switch and the larger ones to the low-pressure switch.

Therefore, to replace the AC low-pressure switch, follow the larger in diameter pipers to find where the switch is located.

Step 3: Once you have reached the low-pressure switch, disconnect the negative terminal of the battery.

This is an important step before doing any sort of work involving an electrical component of your car as it prevents a short to the ground, which, if not prevented, can cause some serious harm to both you and your vehicle.

Also, it is important to know that when you disconnect your negative terminal of the battery, it is likely that you may lose your data to the instrument cluster or the radio.

Step 4: After having the negative terminal of the battery, we can get down to step four of the process of replacing the low-pressure switch. For this step, you will need a wrench.

Using the wrench, loosen the switch. If it is too tight, don’t apply too much pressure as you might damage any of the surrounding pipes.

In case the switch is too tight, and you are having trouble trying to remove it, you can use either some WD-40 or 5-56. Let it sit for a few hours, and it will help you in loosening the switch, so it is easier for you to remove later on.

Also, before removing any of the two switches, make sure that your AC system has an inbuilt check valve, which will prevent the refrigerant from pouring out once the switch is removed.

After you have removed the switch, replaced it with a new one, and you are done.

Final Thoughts

Now you know how to identify that your AC low-pressure switch is not working and then how to located and later replace it.