Air conditioning pressure switches are designed to protect the A/C system against pressure that is too high or too low. There are both high pressure and low pressure switches; some vehicles are equipped with just a high pressure switch while others have both. Incorrect pressure can damage the compressor, hoses, and other A/C system components.
The A/C pressure switch is a type of device called a transducer, which changes internal resistance in response to changes in pressure. The clutch cycling switch measures A/C pressure near the evaporator outlet, and is often mounted on the accumulator. If the incorrect pressure is sensed, the switch will open the A/C compressor clutch circuit to prevent operation. Once the necessary repairs are made to bring the pressure into specification, the switch will allow normal clutch operation.
The most common symptom of a failed A/C pressure switch is an inoperative compressor and lack of A/C.
Part 1 of 3: Locate the A/C clutch cycling switch
In order to safely and efficiently replace your A/C pressure switch you need a couple of basic tools:
- Free repair manuals - Autozone provides free online repair manuals for certain makes and models
- Protective gloves
- Chilton repair manuals (optional)
- Safety glasses
Step 1: Locate the A/C pressure switch. The pressure switch can be mounted to A/C pressure line, compressor or accumulator/drier.
Part 2 of 3: Remove the A/C pressure switch
Step 1: Disconnect the negative battery cable. Disconnect the negative battery cable with a wrench of ratchet. Then set it aside.
Step 2: Remove the switch electrical connector.
Step 3: Remove the switch. Loose the switch with a socket or wrench, then unscrew it.
- Note: Typically, the A/C system does not need to be evacuated prior to removing the A/C pressure switch. This is because there is a schrader valve built into the switch mount. If you have any doubt as to the design of your system, consult the factory repair information before switch removal.
Part 3 of 3: Install the A/C clutch cycling switch
Step 1: Install the new switch. Screw in the new switch, then tighten it until it’s snug.
Step 2: Reinstall the electrical connector.
Step 3: Reinstall the negative battery cable. Reinstall the negative battery cable and tighten it.
Step 4: Test the A/C. Once you’re finished, turn on the A/C to see if it’s working. If not, you should have your A/C system diagnosed by a trained professional.
If you’d rather have someone tack the job for you, the team at YourMechanic offers expert A/C pressure switch replacement.