How to Jump 3 Wire AC Pressure Switch (4-Easy Methods)

From 1998 to the present, at least one person from 58 states died from a car’s heat stroke. Research also shows that a car’s air condition system could be dangerous and life-threatening. It occurs when the AC wire pressure switch is not functioning correctly. For all you know, the AC works fine, but you can’t operate it with the button. Jumping a three-wire AC pressure switch on your own may be all that is required to resolve this issue.

In general, to jump three-wire AC pressure switches, follow these steps.

  • Reset the PCM Fuse
  • Jump the AC Relay
  • Connect the charging plugs
  • Open the gas valves

In this guide, let me demonstrate the full details.

3 Wire AC Pressure Switch Scheme

The AC wire pressure switch is a safety switch situated behind the air condition system. The system contains two pressure switches, the high side pressure switch and the low side pressure switch. Both monitor the AC system in case pressure difficulties might harm the compressor. The pressure switch also keeps tracking the refrigerant, which is also responsible for decreasing heat in the car.

Another role of the pressure switches is to ensure the correct operation of the AC system. The pressure switches are responsible for preventing harm to the air conditioning pressure system.

How to Jump 3 Wire AC Pressure Switch

Repairing an air conditioner on your own is not as simple as it may appear. To open and seal the items precisely, you may need special equipment. While performing repairs, appropriate expertise is essential. It is critical to follow the procedures exactly when completing the application. A minor error might cause severe damage to the entire AC system. If the damage extends to other critical engine systems, you might be in significant danger.

1. Reset the PCM Fuse

PCM fuse

Start the repair by removing the PCM fuse first. PCM fuse stands for Power-train Control Module. It integrates the Engine Control Unit with the Transmission Control Unit. Before beginning the application, you must remove the fuse. Hold down the PCM info button for around 10 seconds until the PCM resets.

2. Jump the AC Relay

AC relays

The best approach to engage an AC compressor clutch manually is to attach a jumper wire directly to the compressor’s wire. Before you begin, make sure the compressor is filled with oil and that you have adequate refrigerant. Connect the wires using the numbers on the label. To operate the compressor clutch, first, bypass the 3 AC pressure switch between B1 to B4. The link transmits a pressure of 0-5 volts to the PCM fuse. According to professional maintenance advice, it is critical to keep the prior readings in mind. To keep the compressor clutch in excellent working order, you can jump any three wires.

3. Connect the Charging Plugs

charging plugs

It is critical to turn off the power before beginning the operation. You may accomplish this by resetting the PCM switch. You may damage the compressor if you try to connect the switch wires while the electricity is ON. Before commencing the charging procedure, you must fill the refrigerant. You may have to wait until the coolant fills and the charging is finished.

4. Open the Gas Valves

gas valves of a car AC

Once the charging is finished, you can open the compressor’s gas valves. Wait until the compressor functions smoothly accordingly. In a hurry, some people destroy the AC compressor. Check the AC temps regularly to ensure that everything is in order. Close the valves and enjoy the cool air inside the automobile.

How to Know if the 3 Wire AC Pressure Switch is Bad

Troubleshooting encompasses a substantial portion of car ownership. If you are doing this independently, there are several apparent sources to determine whether something is amiss with your vehicle. When the Air Conditioning Pressure System begins to deteriorate or fail, it usually emits indications or symptoms that you may then troubleshoot to determine what is wrong with your vehicle. In this manner, you can quickly decide what steps you need to take to fix the concerns and prevent future damage to the car. Here are some of the indications to watch for while testing the AC Pressure Switch.

On and Off AC System

When the air conditioner reaches the optimal temperature for the car, it usually switches off. Defective air conditioning pressure switches frequently experience this difficulty, in which the air conditioner begins to shut down at regular intervals. If this occurs regularly throughout your rides, you may be sure that something is amiss with the system.

Disabled Cooling

If any of the pressure switches fails, the entire system will be unable to perform its function of producing cold air. If this isn’t the case, you may find that the automobile takes longer to cool, indicating a severe problem with the vehicle that you must address.

Compressed Air Stubborn

Continuously switching the AC compressor on and off might cause a switch failure, preventing the AC compressor from performing effectively or, worse, from functioning. Because the compressor is in charge of circulating the refrigerant throughout the system, if these problems emerge, the Air Conditioning Pressure switch will not provide the service it is expected to provide to the entire engine.


Is it possible to bypass AC high-pressure switches?

Yes, AC high-pressure switches can be a bypass to answer the question. But first, figure out why you’re doing it. Please make sure that you temporarily avoid the correct issue before repairing it. After bypassing the AC high-pressure switch, problems may emerge caused by a poorly operating condenser fan motor. So, how do you get around the air conditioner’s high-pressure switches?

You may perform simple stuff like:
– Find the air conditioner pressure switch and unhook the negative battery connections;
– Disconnect the controls, including the electrical connector and the high-pressure switch.
– Install the replacement switch, reconnect the negative battery cable, and reattach the electrical connector switch you removed in step two.
– The final step is to test the air conditioner. (1)

How to jump a low-pressure switch?

Jumping a low-pressure switch is done to test the circuit. What is the purpose of the low-pressure switch? The air conditioning system’s low-pressure switch in the engine prevents the relay from delivering electricity to the air conditioning compressor. One thing to remember is never to jump the low-pressure switch while the engine is running. If you do this, it may just be for a few seconds. If this step is conducted, you may damage the compressor.

To activate a low-pressure switch:
– Start the engine and set the settings to maximum.
– Remove the connection that is connected to the cycling switch.
– Link the wires’ female ports on the disconnected connection.
– Examine the compressor to see if it works. (2)

Take a look at some of our related articles below.

(1) air conditioner –
(2) compressor –

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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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