Relays are used in many circuits throughout your vehicle. One such circuit is that of the A/C compressor. The compressor has a belt driven clutch which is cycled on and off to keep your A/C blowing cool. Power is supplied to this clutch through a relay.
A relay is a simple device composed of a coil and set of contacts. When current passes through the coil, a magnetic field is formed. This field draws the contacts together and completes the circuit.
The electronic control module monitors the status of sensors in your vehicle to determine if the conditions are correct for A/C operation. If these conditions are met, the module will energize the A/C relay coil when the A/C button is pushed. This allows power to flow through the relay to the compressor clutch, turning your A/C on.
Part 1 of 2: Locate your A/C relay
- Owner’s manual
Step 1: Locate the A/C relay. The A/C relay is typically found in the underhood fuse box.
Consult your owner’s manual for the exact location.
Part 2 of 2: Replace your A/C relay
- Protective gloves
- Safety glasses
Step 1: Remove the relay. Remove the A/C relay by pulling it straight up and out.
If it is difficult to grasp, you can gently use pliers to remove it.
- Warning: Be sure to wear safety goggles and gloves at all times.
Step 2: Purchase the new relay. Note the year, make, model and engine size of your vehicle and take the relay with you to your local parts store.
Having the old relay and the vehicle information will enable the parts store to supply you with the correct, new relay.
Step 3: Install the new relay. Install the new relay by aligning its terminals with the slots in the fuse box and carefully push it in.
Step 4: Test the A/C. Test the A/C to see if it’s working. If it is, then you have successfully replaced the compressor relay.
Th A/C compressor relay is a small part that plays a big role, as with many parts in your car. Luckily, it is an easy fix if one goes bad, and hopefully replacing it will get your car’s system back to working condition. If your A/C is still not working, you should have your A/C system inspected by a trained professional.