The A/C compressor clutch must be cycled on and off to prevent the evaporator from icing up, as well as to to prevent compressor damage. An AC clutch cycling switch is used to determine low side A/C pressure (which is directly proportional to temperature). This information is then used by the electronic control module (ECM) to control the compressor clutch. The ECM will cycle the clutch several times a minute to keep both passenger compartment and evaporator at the correct temperature.
The clutch cycling switch is a type of device called a transducer, which changes internal resistance in response to changes in pressure. The clutch cycling switch measures the low side A/C pressure near the evaporator outlet and is often mounted on the accumulator.
Part 1 of 3: Locate the A/C clutch cycling switch
Step 1: Locate the compressor clutch cycling switch. The cycling switch will typically be mounted to the accumulator.
The accumulator is usually found at the back of the engine compartment, mounted to the firewall.
Part 2 of 3: Remove the A/C clutch cycling switch
- Protective gloves
- Repair manuals
- Safety glasses
Tip: You can often get free repair manuals.
Step 2: Disconnect the negative battery cable. Disconnect the negative battery cable with a wrench or ratchet and set it aside.
- Warning: Be sure to put on protective glasses and gloves before working on your vehicle.
Step 3: Remove the switch electrical connector. This is usually a tab that you can push in to remove easily.
Step 4: Remove the switch. Using a wrench or socket, unscrew the switch from the A/C line, finishing with your fingers.
- Note: In most cases, it is not necessary to evacuate the A/C system refrigerant for clutch cycling switch removal. This is because the switch is mounted on a schrader valve. 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 the new switch in by hand, then tighten it until it's snug using a ratchet or wrench.
Step 2: Reinstall the electrical connector. Do exactly the opposite of what you did before.
Step 3: Reinstall the negative battery cable. Reinstall the negative battery cable and tighten it down.
Step 4: Test the A/C. Test the A/C to see if it’s working.
If not, you should have your A/C system inspected by a trained professional.
Hopefully, if your AC was not working, then it is now. Even though this is a straightforward job, you may want someone else to do the dirty work for you. In that case, the team at YourMechanic offers expert clutch cycling switch replacement and would be happy to come to your home or place of business to perform the job for you.