How to Jump 3 Wire AC Pressure Switch: Simple Steps

This post may contain affiliate links. If you make a purchase through links on our site, we may earn a commission.

How to jump 3 wire AC pressure switch is a question many vehicle owners with such a pressure switch have in mind.

How To Jump 3 Wire Ac Pressure Switch

Such a pressure switch works by utilizing three wires and jumping these three wires is a relatively easy process that can be used to bypass the pressure switches during troubleshooting and diagnostic testing.

This article will provide you with a step-by-step guide on how you can jump a 3 wire AC pressure switch in your vehicle. You can check out these steps below.

How To Jump 3 Wire AC Pressure Switch in Easy Steps?

To jump 3 wire AC pressure switch in easy steps, the first step is to try resetting the PCM fuse. After that, carefully remove the AC relay from the fuse box and connect the charging connectors. Lastly, open the gas valves in a safe and level location.

– Resetting the PCM Fuse

Resetting the Powertrain Control Module fuse, also known as the PCM fuse, is an important step when jumping the 3 wire AC pressure switch in a vehicle. Although the process may vary depending on the make and model of the vehicle, there are some general steps you can follow.

Firstly, you need to locate the PCM fuse. The PCM fuse can be found in the engine compartment fuse box or under the dashboard on the driver’s side of the vehicle. To determine the location of the PCM fuse for your car, you can refer to the owner’s manual or a repair manual.

After you have located the PCM fuse, turn off the engine. This step is crucial before attempting to reset the PCM fuse. Then, use a fuse puller or needle-nose pliers to carefully remove the PCM fuse from the fuse box. Be sure to keep the fuse in a safe place so that it doesn’t get lost.

Next, wait for at least 15 seconds before replacing the PCM fuse. This will allow the system enough time to fully power down. After waiting for a while, carefully insert the PCM fuse back into the fuse box, making sure it’s fully seated.

Now turn on the ignition without starting the engine. This will power up the vehicle’s electrical systems. Wait for several seconds to allow the system to reset. This process may take a few minutes, depending on the vehicle.

It’s important to note that you should only proceed with this procedure if you are certain about what you are doing. If you have any doubts or face any problems at any point in the procedure, you should seek professional help immediately.

– Jumping the AC Relay

Jumping the AC relay is the next thing you should do for jumping 3 wire AC pressure switch in a vehicle. This will help diagnose issues with the vehicle’s air conditioning system as well. You should keep in mind that the exact process of this step may vary depending on the make and model of the vehicle. However, here’s a generalized way.

Jumping the AC Relay for AC Pressure Switch

First, you must locate the AC relay. The AC relay is usually located in the engine compartment fuse box or under the dashboard on the driver’s side of the vehicle. The owner’s manual or a repair manual for your vehicle should indicate the location of the AC relay.

Now, use a fuse puller or needle-nose pliers to carefully remove the AC relay from the fuse box. Be sure to keep the relay in a safe place so that it doesn’t get lost. Next, look at the bottom of the AC relay to identify the pins. There are typically four pins: two larger pins and two smaller pins.

After that, use a multimeter to locate the power pin, which should have a constant 12V supply even when the ignition is turned off. This pin is usually one of the larger pins. Then use the multimeter to locate the signal pin, which should have a 12V supply only when the ignition is turned on and the AC is switched on. This pin is usually one of the smaller pins.

After identifying the pins, use a small piece of wire or a paper clip to connect the power pin and the signal pin. This will jump the relay and bypass the pressure switch. Then turn on the car’s ignition without starting the engine. This will power up the vehicle’s electrical systems.

Next, turn on the AC to see if it works. If the AC still doesn’t work, turn off the AC and the ignition, then remove the jumper wire from the power pin and signal pin of the relay. Then you should proceed to the next step.

– Connecting the Charging Connectors 

Connecting the charging connectors for a 3 wire AC pressure switch in a vehicle is an important process that is necessary to ensure the proper functioning of the air conditioning system. To begin, the low-pressure charging port needs to be located.

This port is usually located on the suction side of the compressor, near the firewall, and is typically marked with an “L” or a blue cap. Once the low-pressure charging port has been located, the low-pressure line should be identified. The low-pressure line is usually the larger of the two AC lines and is located between the compressor and the evaporator.

After the low-pressure charging port and low-pressure line have been located, the charging hose can be attached to the low-pressure charging port. The end of the charging hose should click into place, creating a tight seal. The valve on the charging hose should then be slowly opened to allow refrigerant to flow into the system.

It is important to monitor the pressure gauge on the charging hose during this process to ensure that the system pressure stays within the recommended range for the vehicle. Overcharging or undercharging the system can cause damage to the compressor or poor cooling performance.

If the pressure goes beyond the recommended range, the valve on the charging hose should be closed, and the amount of refrigerant in the system should be checked. It is important to periodically shake the can of refrigerant during the charging process to ensure that the refrigerant is being transferred correctly.

Once the system pressure reaches the recommended range, the valve on the charging hose should be closed. The charging hose should then be removed from the low-pressure charging port, taking care not to spill any refrigerant.

Finally, it is essential to check the AC system for leaks using a UV dye or electronic leak detector. If any leaks are detected, they should be repaired before adding more refrigerant to the system.

– Opening the Gas Valves

The last thing you need to do to jump a 3 wire AC pressure switch is to open the gas valves. For this, make sure the vehicle is in a safe and level location. This is a crucial step to ensure that the vehicle is safe to work on. Park the vehicle on a flat and level surface and turn off the engine. Now you have to locate the gas valve in the engine compartment of the vehicle.

Ac Pressure Switch Is to Open the Gas Valves

The gas valve is usually attached to the fuel injector rail or the fuel pump, while the AC pressure switch is located on the AC compressor clutch. Now you have to identify the wires of the 3 wire AC pressure switch. The switch has three wires, each of which is labeled. The “common” wire is usually black, the “normally closed” wire is usually blue, and the “normally open” wire is usually red.

You have to connect the “common” wire of the AC pressure switch to the common wire of the gas valve. This wire is usually black in color and is connected to the ground. After that, the “normally closed” wire of the AC pressure switch should be connected to the “TH” or “TH/TR” terminal of the gas valve. This wire is usually blue in color and is connected to the control circuit of the gas valve.

Next, the “normally open” wire of the AC pressure switch should be connected to the “TR” or “TH/TR” terminal of the gas valve. This wire is usually red in color and is connected to the control circuit of the gas valve. Finally, it’s important to double-check all wire connections to ensure that they are correctly placed and securely tightened. Loose connections can cause the gas valve to malfunction or even be a safety hazard.

After turning on the engine, check the gas valve for proper functioning. Verify that the pressure switch is open when the AC system is not in operation and closed when the AC system is in operation. This will ensure that the gas valve is working correctly and supplying the correct amount of fuel to the engine.

How Do You Test a Three-Wire AC Pressure Sensor?

To test a three-wire AC pressure sensor on a vehicle, you need to locate the pressure sensor near the compressor first. Then you have to disconnect the electrical connector to ensure that there is no power flowing to the sensor and prevent any accidental electrical shock.

Next, you have to use a multimeter to check the resistance of the common, normally open, and normally closed terminals. Set your multimeter to read resistance (ohms) and touch the probes to the terminals on the sensor

To check the resistance of the common terminal with the normally open and normally closed terminals, touch the red (positive) probe of the multimeter carefully to the common terminal and the black (negative) probe to the normally open terminal. The resistance should be infinite, which means the circuit is open.

After that, you have to check the resistance of the normally open terminal while applying pressure to the sensor. Next, you should check the resistance of the normally closed terminal while releasing pressure from the sensor. Finally, you can interpret the results and replace the sensor if the resistance values are outside of the specifications provided by the vehicle manufacturer.

Know When Your AC Pressure Switch Needs To Be Jumped

If your air conditioning system is not running and the cause is due to the AC pressure switch, you may need to jump the switch temporarily to diagnose the problem. To determine if the AC pressure switch is causing the issue, you can use a multimeter to test the switch’s continuity. If there is no continuity, the switch has tripped and needs to be reset or replaced.

System is Not Running Due to The Ac Pressure Switch

Alternatively, if you see any visual damage or leaking from the switch, it may need to be replaced. It is always best to consult a qualified mechanic to diagnose and repair any issues with your vehicle’s air conditioning system.

Frequently Asked Questions

1. What Does Jumping the AC Pressure Switch Do?

Jumping the AC pressure switch bypasses its function to allow the air conditioning system to run even if it detects a low or high-pressure issue. The AC pressure switch is an essential safety feature in the air conditioning system that prevents damage to the compressor.

It is able to do this by detecting low or high-pressure conditions in the refrigerant circuit. When the switch detects low or high pressure, it will interrupt the power supply to the compressor, which will prevent it from running.

By jumping the AC pressure switch, you are temporarily overriding its safety function to allow the air conditioning system to run. It is always better to address the underlying issue and have the AC pressure switch repaired by a qualified professional rather than bypassing it.

2. Can Jumping the AC Pressure Switch Harm Your Vehicle’s AC System?

Yes, jumping the AC pressure switch can potentially harm your vehicle’s AC system. By jumping the AC pressure switch, you are effectively bypassing this safety feature and allowing the compressor to run even if there is a low or high-pressure issue present.

This can cause the compressor to overheat and fail, which can result in costly repairs due to no auto repair or even a complete replacement of the system. In addition, running the compressor under low or high-pressure conditions can cause damage to other components in the system, further adding to the potential harm to your vehicle’s air conditioning system. Therefore, while jumping the AC pressure switch may seem like a quick fix for air conditioning issues, it is not a recommended practice.

If you are experiencing problems with your vehicle’s air conditioning system, it’s best to have it diagnosed and repaired by a qualified professional who can address the underlying issue and ensure that the system is operating safely and efficiently. This will help to prevent potential harm to your vehicle’s air conditioning system and ensure that it continues to function properly over the long term.

Conclusion

After reading through the guide on how to jump 3 wire AC pressure switch, there should be no more confusion.

However, before attempting to perform the procedure, there are some essential points to keep in mind.

  • One of the most essential things to note is that different vehicles may have different configurations for the components mentioned in the guide. Therefore, it is crucial to learn about the specific details of your vehicle to avoid any complications.
  • Another crucial point is to always follow the manufacturer’s manual for your vehicle and not attempt the procedure unless you are certain you have understood the steps correctly. This is to ensure that you do not cause any further damage to your vehicle.
  • If at any point during the repair procedure, you feel confused or face any problems, it is highly recommended to immediately consult professionals. Attempting to continue the repair without the proper knowledge and tools can result in further damage or injury.

In conclusion, if you have a solid understanding of your vehicle’s manufacturer instructions and safety guidelines, you can confidently proceed with working on the AC pressure switch. It is important to prioritize safety and seek professional help if needed.

5/5 - (12 votes)
Ran When Parked