How to Install a Car Air Compressor Pressure Switch

The air compressor pressure switch turns the motor that controls the air conditioner compressor motor. When it goes bad, your car’s air conditioner may not work at all. Air conditioning system are expensive to repair. If you follow a few steps, you can do the repair yourself and save yourself the money.

Tools and Materials

  • Screwdriver
  • Wire strippers
  • Crescent wrench
  • Teflon tape
  • Correctly rated air compressor switch
  • ¼ pipe nipple to conduct air from storage tank (optional)

Step 1: Cut the Power

The first step is to eliminate all the electrical power that runs to the circuit feeding the air compressor. You want to make sure that nothing can turn on while you are doing your repair. Coming into contact with belts or fans can cause injury. Also, coming into contact with refrigerant can be harmful. While you eliminate the power, you will be able to see the correct rating for your air compressor pressure switch. It can be found on the storage tank. It is important only to install a switch with the proper rating.

Step 2: Install Pipe Nipple

Luckily, you do not have to install a valve between the air compressor pressure switch and the air storage tank. Instead, you use a pipe nipple. One is usually pre-installed on the storage tank. You can replace it with a new one, but the original can also stay where it is if it appears to still be in good working order. If you are replacing it, do that now.

Next, wrap the male pipe ends on your air compressor pressure switch with sealant tape. Wrap the threads about two or three times. Next, screw the female fitting of the switch onto the pipe nipple. To ensure it is secure, tighten with a crescent wrench.

Step 3: Connect Wires

Take the top off of the switch and you will see four contacts. The 2 wires are from the power source and the compressor, they will need to be connected. Use your wire strippers to remove about 1 inch of insulation from each wire and expose the copper wire. With your screwdriver, connect the wires from the power source to the outside screws of the contacts. They are likely labeled “line.” Next, connect the wires from the motor to the inside screw contact terminals, which may be labeled “load.”

Step 4: Mating Wires

Depending on your feeder circuit, you may need to mate the wires. For a 240 VAC circuit, it is unnecessary. For a 120 VAC circuit, the neutral white wires need to be connected to the same screw contact terminal. They should be attached to the green screw located on the metal frame of your air compressor pressure switch.

Now, put the cover back and restore power to the circuit. Do not attempt to adjust the factory setting on your switch. This can over pressurize your air conditioner and cause damage. Last, all you need to do is switch your air compressor pressure switch to the on position and you are ready to go.