Learning, Wiring,

How to Jump 4 Wire AC Pressure Switch? (3 Easy Steps)

If you have trouble jumping or bypassing a 4-wire AC pressure switch, this article will solve all your problems.

It is possible that your vehicle’s 4-wire AC pressure switch can become faulty or completely useless. You should know how to bypass a 4-wire AC pressure switch for that situation. 

In general, to jump or bypass four wires AC pressure switch:

  • Locate the AC pressure switch.
  • Identify the INPUT and OUTPUT terminals correctly.
  • Connect the INPUT and OUTPUT wires.

Read the below article for a more in-depth explanation.

3-Step Guide on How to Jump 4 Wire AC Pressure Switch

Sometimes, your vehicle’s AC system might malfunction, or you might hear some weird sound from the AC system. Either way, it could indicate a bad AC pressure switch. You must replace or bypass the AC pressure unit to solve this issue.

If you use a 2-wire air conditioning pressure switch, bypassing it won’t be a big issue. Just connect the INPUT and OUTPUT wires.

However, when it comes to 4 wire AC pressure switch, there are four wires, and the bypassing process is a little bit difficult. With that in mind, let’s follow our 3-step guide on bypassing a 4-wire AC pressure switch.

Things You’ll Need

  • Digital Multimeter

Step 1 – Locate the AC Pressure Switch

First and foremost, locate the air conditioning pressure switch. The AC pressure switch will most often be located on the air conditioning pipes (close to the air compressor).

Also, you can refer to the vehicle manual to find the exact location of the AC pressure switch. Or do some internet research according to your vehicle model. Either way, you’ll be able to locate it without much trouble.

Step 2 – Identify the INPUT and OUTPUT Terminals

After locating the AC pressure switch, you’ll see four different terminals on the switch. You should be able to identify the correct INPUT and OUTPUT terminals. To do that, you’ll need a digital multimeter. And here are steps for identifying INPUT and OUTPUT terminals.

  1. Set the multimeter to continuity settings.
  2. Place the red multimeter probe on any terminal.
  3. Place the black lead on another terminal and check for continuity.
  4. Check all terminals as fairs until you detect continuity.

The two terminals that show continuity are the INPUT and OUTPUT terminals. When you connect the multimeter probes to the correct terminals, you’ll hear a beep sound from the multimeter.

Remember: The AC system should be turned off while you check the continuity. 

How To Set the Multimeter to Continuity Settings?

Setting your digital multimeter to continuity settings is quite easy. Here are the appropriate steps that you should follow.

  1. Turn the multimeter dial to the continuity symbol. The triangle with the line is the continuity symbol.
  2. Insert the blackjack into the multimeter’s COM port.
  3. Insert the red jack into the multimeter’s V/Ω port.
  4. Turn on the multimeter.
  5. Now your multimeter is ready to check the continuity of any object.

Step 3 – Connect INPUT and OUTPUT Wires

Now you are all set to bypass the 4-wire AC pressure switch. Loosen the INPUT and OUTPUT wires from the AC pressure switch.

Then, connect those two wires. That’s it; you now successfully bypass the 4-wire AC pressure switch.

Few Ways to Identify Bad Pressure Switch

Before you bypass the AC pressure switch, it is always important to identify whether the AC switch is bad or not. Otherwise, you’ll waste time and energy. Here are a few common signs.

Constant AC System Power On and Off

If you experience unwanted power on and off in your AC system, it could be because of a bad AC pressure switch. For instance, the AC switch ensures the system turns off when the idle temperature is reached. But a faulty switch might disrupt this operation.

Cannot Cool the Vehicle

When the AC pressure switch goes bad, the system faces difficulties maintaining the required pressure. This will affect heavily in the vehicle cooling process. You might experience that reaching idle temperature takes more time than usual. Or sometimes, the vehicle won’t reach the idle temperature at all.

Is It Safe to Bypass the AC Pressure Switch?

That depends on the timeframe. The above bypassing process is a temporary solution, and running your vehicle with a bypassed AC pressure switch is not recommended. If you do so, you might damage the AC system.

Hence, use this process as a temporary solution and repair the switch soon as possible. It will cost you some money, but you will prevent long-term damage to your vehicle’s AC system.

Video Reference

The Car Doctor

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About Sam Orlovsky

AvatarCertifications: 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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