4 Steps To Jump The 3 Wire Ac Pressure Switch For Your Car’s AC System

What better than a comfortable air conditioned drive on a hot sultry day? On peaking summers, it becomes challenging even sit in the car if there is a faulty or bad AC system. The air conditioner systems within the vehicles work with a specific pressure switch. 

At times, you might experience trouble turning on the faulty switch, which will deprive you of chilled and comfortable drive during summers. You might have to seek some repairs all by yourself or take your car to an expert for the same. 

One ideal solution is to jump the three-wire switch to control the AC system. 

Be confident that you don’t need an expert to help you fix the air conditioner! You can make an effort to make this jump all by yourself. This article intends to help you with the necessary guidance and information on approaching this procedure.

4 Easy and Tested Way To Jump 3 Wire AC Pressure Switch 

The following are simple and tested techniques that will help you jump 3 Wire AC pressure. We have tested these simple techniques, and without a doubt, we recommend them to you. 

The following are simple steps to jump your wire AC without. 

Step 1: Reset Power-train Control Module (PCM) Fuse

The first simple technique is getting rid of the PCM fuse. This will allow you to start repairing procedure. PCM combines Engine Control Unit together with the Transmission Control Unit. 

Therefore, before you start resetting it, you need first to pull out the fuse. Once the fuse is out, we will be ready to get started. 

Step 2: Jump AC Relay

Check the numbers printed on your AC and connect wires according to it. You need to bypass the 3 wire AC pressure switch through the B1 to B4. This is done to power the compressor clutch. 

When you do this, the connection will send 0-5 volts of pressure through the PCM fuse. 

However, in this step, you need to pay close attention to the numbers printed on the AC in mind. This will help you jump all three wires to keep your compressor working in good condition at all times. 

Step 3: Connect The Charging Connectors

This is the main reason we began by removing the PCM switch in step one. If you haven’t removed the switch, you will end up damaging your compressor in this third step. Connecting the connectors to the charging with switch wires ON will damage the compressor. 

So, at this step, ensure your switch has been reset, and its wire isn’t on. Also, ensure before you connect to the charging connectors your fill up the refrigerant. The last thing you have to do in this step is to wait for the charge to complete and the coolant to fill.

The last thing you have to do in this step is to wait to charge to complete and coolant to fill. 

Step 4: Open Gas Valves

After the charging completes, open the gas valves on your car. Wait until the compressor starts running properly. 

Don’t pressure the compressor to run faster. If you do this, you will end up damaging it. 

Also, remember to check AC temperatures and make sure they are running normally. And once you ascertain that everything is fine, close the valves and enjoy a cool breeze from your car cabin. 

What Happens If I Damage My Compressor? How To Jump 3 Wire AC Pressure Switch

If, in the process of jumping your 3 wire AC pressure switch, you damage your compressor, don’t panic. All you will need to do is buy another compressor and replace the damaged one. 

The good news is that these compressors are available on Amazon. You just order and buy the compressor that most suits your car and replace the damaged compressor. 

A new OEM Class AC Compressor is an effective compressor that will fit in most cars. You can buy it and replace your damaged compressors. It will give you great performance. 

Click here to check the latest price and buy it from Amazon today. 

How Do I Know When My 3 Wire AC Pressure Switch Needs Jumping? 

First, before you think of jumping your 3 wire AC pressure switch, you first need to know that it needs jumping. Sometimes you might think your AC needs repair, but that might not be the case. Something else might be a problem. 

Therefore, if you notice any of the following signs, know your AC needs attention. 

#1 Unable to Cool the Car

When you see the knob of your AC to maximum, but still you can’t feel the coldness, this is a clear sign that your AC pressure switch is defective. 

When the AC is not cooling your car cabin, it simply shows that the system doesn’t preserve enough AC to keep it running. And as a result, the AC system doesn’t emit sufficient cold air for keeping conducive temperatures. 

Other times, you will notice that your AC will take a longer time than expected to cool the cabin. If this is happening, you need to check at the switch. 

And worst of it all will happen when your AC can’t cool your car cabin at all. 

Read Also: How To Remove Stuck Oil Drain Plug

#2 Unstable AC System

An AC operates by repeatedly making on and off-cycle. In this case, when the sensors detect the right temperatures, the AC turns itself automatically. 

However, when you see instabilities in turning on and off, then you need to check it. 

For instance, this will happen when your car hood becomes colder and colder, and the AC continue supplying cold air. This will mean that the AC is not accepting triggers from the sensor to stop a certain level. 

Some other times, you might see the AC turning itself off even before it cools the hood. In this case, you also need to get it checked. It’s a sign of some problem. 

In short, you will know there is a problem when turning on and off is unstable for your car AC. 

#3 Compressor is Off

When you notice that your compressor is not turning on when required, then there is a problem. The AC pressure switch is responsible for turning on and off the compressor. And if the compressor fails to turn on, then the switch is the problem. 

If the AC switch fails, the compressor also fails. 

The main role of the compressor is to supply refrigerant to the AC system. It’s responsible for delivering cool air in your car cabin. And if it can’t do so, then you need to check the AC pressure switch and make sure it’s working as required. 

#4 Complete Breakdown of the AC

It is an even more serious issue than that of the intermittent cooling output of your car’s AC system. If your AC system goes into a complete breakdown, then the refrigerant pressure switch sensor might just become defective. 

But the point of consideration is that the pressure switch is just one aspect that might trigger this symptom! Many components within a particular vehicle AC system might malfunction to cause the system to break down.

So, follow the steps to jump the 3 Wire AC pressure switch and check if the issue persists. If the AC still fails to work, you will have to take it to the garage and get an in-depth diagnosis.

#5 Blowing Warm Air

As soon as you turn on the air conditioning, you expect to get a cold breeze out of the vents. But if the pressure switch is malfunctioned or goes bad, then you might end up getting warm airflow inside your cabin. 

But this is again just one cause of this symptom, whereas low refrigerant levels can also cause this symptom. Therefore, check all aspects before considering the pressure switch jump.

#6 Noises From The Air Conditioning System

If the compressor of your AC system is switching on & off, you will probably notice some of the specific changes in it. This will sound like the click occurs when the compressor starts, but the air won’t flow from the vents. 

These click sounds might differ from those you hear when the AC is fully functional. Take note of it, and you might realize that something is not right with the system.

Working of a Pressure Switch

Before you get started with the steps to jump 3 wire AC pressure switches, you must have a brief idea of the pressure switch. It is a device with an operational capability with electric contact when it reaches a preset fluid pressure. 

The switch will then make electrical contact with that on the pressure rise or fall from a certain preset level. These switches are highly used for both residential as well as industrial applications. 

Some specific types are also ideal for air conditioning in cars and refrigeration. Some of the specific applications of pressure switches are compressed air systems, pneumatic & hydraulic systems, furnace & boiling systems, filtering & screening equipment, and others. 

The working of a pressure switch is accountable for monitoring the high pressures of the A/C loop. Hence, it enables or disables the compressor based upon the pressure thresholds. 

There is supposedly an additional circuit that controls the cooling fan of a car air conditioner. Hence, this secures the condensation process, which forces the air to flow through the condenser. 

In simple words, the pressure switch is considered a safety device for the AC loop. It is located at the high-pressure end of that loop and has different roles to play:

  • It helps in monitoring the high pressure of the loop. 
  • It detects too low and too high pressure. 
  • It consists of an additional threshold to activate the maximum speed of the AC’s cooling fan. 

Purpose of Pressure Switches in Air Conditioning System of Cars

The AC pressure switch is considered a safety valve for the car’s AC system. It is located right behind the installed system. It comes with two pressure switches: high side and low side pressure switches. 

Both of them are responsible for protecting the complete AC system if any pressure problem damages the entire compressor. The pressure switch also monitors the refrigerant, which is responsible for reducing the heat produced within the vehicle. 

Apart from that, the pressure switches take the mantle of protecting the AC system from experiencing damage. The complete AC system works around five significant parts that process collectively to make it work. 

The pressure switch works upon maintaining this functionality and protecting it! The five major parts of a vehicle AC system are:

#1 Compressor

This part of the entire air conditioning system is the most essential part of the complete AC system. The cold breeze that you feel within the car’s cockpit is the work of the compressor. 

The process of execution of the compressor is to put the pressure in the refrigerant and cool the air. It directs the air to pass through the condenser. Moreover, it also has other features, such as sensing the temperature shifts inside and outside the car. 

There are sensors in it to constantly monitor the temperature within the car. Modern vehicles call such systems a Climatic Control AC System. 

#2 Condenser

The compressor works collectively with that of the compressor. The compressor does the work by imposing pressure upon the refrigerant, and the condenser controls the pressure and temperature that come from the refrigerant. 

The condenser is also responsible for moving the ventilated liquid refrigerant to the accumulator. Hence, this is the working efficiency of a condenser. 

#3 Accumulator/Drier/Receiver

The accumulator is not any standard component in all of the AC systems of different vehicles. Some brands embed it in some specific car build to make the car’s correct valuation and cost-cutting. 

Even though it is not standard, it is still a necessary component for the AC system. Its working determines the separation of the gas from liquid in the air conditioning system. It is a crucial part of the entire process because the compressor is not built to handle liquids. 

The compressor will experience damage when it mixes up with the liquid within it. The prime purpose of the accumulator is to accumulate the excessive refrigerant! 

Moreover, it also helps filter out the debris and eradicate the moisture that persists within the air conditioning system. And finally, it regulates the existing refrigerant which enters into the evaporator. 

#4 Thermal Expansion Valve

The thermal expansion valve is also termed the orifice tube. It is located between the evaporator & condenser. This component aims to work collectively with the condenser to monitor the necessary pressure. Hence, it ensures that just the safe refrigerants should enter the evaporator.

#5 Evaporator

Evaporator has prime importance amongst all of the components which work in the back-end for seamless functioning of the air conditioner system. The evaporator is located right behind the dashboard, cools the air with refrigerant, and is then blown into the cabin of your car.

How To Test The Ac Pressure Switch Of Your Car?

If you have some basic knowledge of car mechanics, you can follow the below-specified measures to determine if your car needs to jump off a 3 wire AC pressure switch. These are the measures that you can try to test the AC pressure switch and its functioning efficiency:

#1 Turn On The Air Conditioning System

Ignite the car and leave it in a running state! Now turn on the air conditioning system to its full potential. You need to make sure that the car’s windows are open so that the air doesn’t go on cycling itself. 

The first sign to note for determining if the AC pressure switch is bad is when the system shuts on and off intermittently. This symptom should occur when the windows of the car are open! Hence, this indicates that you need the jump of a 3 wire AC pressure switch. 

#2 Note The Functions Of Condenser Tubes

Go ahead and pop the hood of your car and look for the condenser. If you do not know which engine part is a condenser, you should look for a block component with a grille shape that connects to the compressor with hoses and tubes. 

It will have a belt and pulley system. You need to feel both tubes coming out of the condenser and connecting with the firewall. Do it while the car’s engine is still running and the air conditioner is turned on! 

Both the tubes should be cold to touch and feel because of the refrigerant flowing through them. If any of the tubes are not cold, you can conclude that there is no refrigerant moving in that tube line. 

Hence, this indicates that the pressure switch might have been affected or has experienced some faults. In this scenario, a jump becomes necessary! 

#3 Check The Ac Pressures

You will need an air conditioning gauge for checking the pressure levels on both sides. You need to attach the low-pressure gauge to the low-pressure fitting and the high-pressure gauge to the high-pressure fitting. 

On the low-pressure side of the gauge reading, you should get the output as 30 PSI for the outside temperature of 90 degrees Fahrenheit or less. Similarly, the high-pressure side of the gauge should give a reading of 50PSI with twice the ambient temperature on the outside. 

#4 Scan For Any Trouble Codes

You can use the OBDII port on your car and use the code scanner to check for any error codes that pop up. These error codes will indicate any of the possible errors within the pressure switch of your AC system. 

Once you fix the problem, you can come back and use the code scanner to erase those codes. If you do not want to buy an engine code reader, then you can take a halt at your service center and ask them to do it for free.

#5 Check The Electrical Connections

Turn off the pressure sensor and test the specified connection that heads to the sensor from the electrical harness. You need to be sure that the key is turned on to the spot where you can access all of the electronic utilities of the car. If all of the electrical connections are working well as they should, then the multimeter will give a reading between 4.0 volts to 5.0 volts.


Is it Safe to Bypass the AC Pressure switch?

The AC pressure switch exists to protect the system from experiencing damage if the refrigerant level is lower than the required amount. If the switch is correct, there is no need to bypass it. It exists for a reason, and you should not count on bypassing it because your AC system can undergo serious repairs with high expenses without it. 

How to know if the AC Pressure Switch is Bad?

The most common symptom of a bad AC pressure switch is intermittent air condition functionality. This is the most common symptom that vehicles with bad AC pressure switches go through. 

This symptom is more observant during the summer season. If this is the condition, you can conclude that the AC pressure switch is bad. 

What is the Purpose of a Low-pressure Switch? 

The low-pressure switch intends to monitor AC’s refrigeration system for tracking the refrigerant charge. It might also help the evaporator or indoor coil stop frozen due to the low airflow or dirty filter. 

The low-pressure switch connects to the suction or low-end side of the system to sense the suction pressure. When pressure within the AC system exceeds the setting of the high-pressure switch, the pressure switch will open the circuit within the compressor clutch. Hence, the compressor will stop the circulation of the refrigerant.

Final Verdict 

Whenever you notice any of the symptoms of a defective 3 wire AC pressure switch, it’s time to get it repaired. However, before you do anything, it’s essential to check the symptoms of a defective AC switch. This will help you ensure you are dealing with the real problem that causing trouble to your cabin cooling. 

Once you are sure, the AC switch is the problem. Apply the simple steps we have shared with you in this article.

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