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Malfunctioning AC Pressure Switch Symptoms And How To Replace

More and more functions are getting introduced to automobiles these days, and one of the common ones is having the air conditioner in your car. A working AC is no less than a blessing in those humid summer days. However, you may find that there is something wrong with the system and the inside is not getting chilly enough. Well, a faulty AC high pressure switch or AC low pressure switch can be the culprit. Getting to know about malfunctioning AC pressure switch symptoms can be a great help so you can replace it immediately.

ac high pressure switch
Getting to know about malfunctioning AC pressure switch symptoms can be a great help so you can replace it immediately.

What Is The AC Pressure Switch?

If you want to know what AC pressure switch is, then you should know how AC actually works.

Ac system

The Air conditioning system in a car is actually a pretty complex system and it works based on 2 basic principles. 

Firstly, the compressor, connected to the engine via a high pressure line, adsorbs the refrigerant in the gas form from the gas tank and compresses it at high pressure. When it is compressed, the refrigerant temperature rises and it is pushed to the condenser, located at the front of the car, near the radiator and has its own fan. In the condenser, because of the heat dissipation at high pressure, the refrigerant becomes liquid and switches to expansion valve.

Secondly, at the expansion valve, the pressure drops suddenly so the refrigerant vaporizes and moves to the evaporator. Here, it draws heat from its surroundings which leads to the drop of the temperature. Cold air will be blown to the environment by the blower. The wind blowing from the evaporator can be either external (external cooling), cabin wind or both.

ac low pressure switch symptoms
The Air conditioning system in a car is actually a pretty complex system and it works based on 2 basic principles.

Learn more about how the car’s air conditioning system works here.

AC pressure switch

AC splits into two halves, one is low pressure half and the other is high pressure and both sides are equipped with an AC pressure switch. So what do these switches do? AC high pressure switch and low pressure switch monitor the pressure of the refrigerant on both the low and high pressure side of the system. 

ac high pressure switch symptoms
AC splits into two halves, one is low pressure half and the other is high pressure and both sides are equipped with an AC pressure switch.

They are very important safety devices that are built into the AC system because if the pressure is too low or too high, it can cause serious damage to the AC system. If the pressure is too low, then the risk is that the compressor can burn out. It will then be unable to compress the refrigerant from liquid to fluid, which will see your car AC unit grind to a halt. If the pressure is too high, it could burst the compressor causing a leak of refrigerant fluid. It is going to grind to a halt again if there is no fluid in the system.

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Identify The Faulty AC Low Pressure Switch Symptoms & AC High Pressure Switch Symptoms

If the pressure is too low (AC low pressure switch), the compressor risks damage due to running with low oil. If it is too high (AC high pressure switch), the compressor is at risk of overheating and becoming damaged. Depending on which side of the system the sensor is mounted in, when the pressure rises too high or drops so low, the AC pressure switch will turn off the compressor to prevent damage from occurring. As the AC high pressure switch and low pressure switch serve to protect the compressor and rest of the system from damage, they play an important role for the proper function and service life of an AC system, so they should be replaced if they are causing any problems.

symptoms of bad ac pressure switch
There are easy tips to identify things that take place only when the AC pressure switch malfunctions.

Here are some easy tips to identify things that take place only when the AC pressure switch malfunctions. Let’s hover on symptoms of bad AC pressure switch!

1. When The Compressor Fluctuates

The first symptom which can answer the question “how to tell if AC pressure switch is bad”. The AC system in a car works automatically and gets switched off once it reaches a certain point of pressure. However when an a/c pressure switch malfunctions, you may notice it is fluctuating or getting on and off repeatedly. This can be easily noticed when you are idling the car; you can have a look at the RPM and see how often it fluctuates. It is one of the common AC pressure switch symptoms you can notice in the first place.

how to tell if ac pressure switch is bad
The first symptom which can answer the question “how to tell if AC pressure switch is bad” is the fluctuation of compressor.

2. When It Is Not Getting Cold Enough

Another AC pressure switch symptom is not getting cold enough. In case of an auto air conditioner pressure switch fails, it transfers a signal to the system, and as a result, the AC turns off. The faulty pressure keeps your car’s aura from getting cool down. The system gets shut off and it does not reach the specific temperature. Thus, if it is getting longer to cool the interior than usual, it may be a sign. For more, read out the maintenance tips by experts online.

ac pressure switch symptoms
In case of an auto air conditioner pressure switch fails, it transfers a signal to the system, and as a result, the AC turns off.

3. Or If The AC Does Not Work At All

It is not mandatory for an AC switch to act faulty, and in some cases, it can go non-functioning as well. Hence, the switch failure keeps the AC from performing at all, and it does not cool the inside of your car. It can be a prominent symptom that you need a replacement for the pressure switch. Let the mechanic analyze if it is a fault of an AC high pressure switch or a low one.

ac pressure switch
The switch failure keeps the AC from performing at all.

Replacing The Out Of Order AC Pressure Switch

Encountering any of these symptoms in your car clearly indicates that you need AC high pressure switch replacement or AC low pressure switch replacement.

 Let’s get started on DIY:

1. Find The Sensor And Disconnect The Negative Battery Саblе

Start with locating the sensor as in some cars it can be an AC high pressure switch function, and in some, a low one. Whatever this sensor is, you can locate it in the engine bay area. Once you are done finding the sensor, take off the negative battery саblе to keep the process safe.

2. Install The New Sensor

Take off the old sensor by unscrewing it and get ready to screw a new one. Read out the manual of your car for any specific instructions no matter if you detect AC high pressure switch symptoms or the low pressure switch.

3. Screw All The Parts Back

The last step is to tighten all the parts back to work, and now you should see a working AC system.

Learn more how to replace the AC pressure switch in the video below.

The Crux

It is best to hire a professional once you detect any of the faulty AC pressure switch symptoms. Getting a DIY can be the case though but if you are a novice and do not want to try your hands on with technicality, it is best to hire the expert and enjoy that cool gust again. Follow us to know more about car maintenance tips.