With all the spinning, stretching, and heating up that the A/C belt does, it's not surprising for it to eventually wear out-especially without the right tension. To ensure that your A/C belt receives the proper tension, make sure to check on the A/C belt tensioner pulley. If you hear a high-pitched squealing noise every time you power up the air conditioning in your car, it's probably time to change your worn-out pulley.
Step 1: Turn off your car engine and let it cool down for a couple of hours.
Step 2: Pop the hood open and locate your A/C belt tensioner.
Step 3: Remove the nut on the center of the A/C belt tensioner pulley with your ratchet and the proper socket. Use some rust penetrator if the nut is difficult to remove.
Step 4: Loosen the adjustment bolt on the A/C bracket to lessen tension on the A/C belt.
Step 5: Remove the A/C belt. Depending on your vehicle, you might have to remove or displace other parts before getting to the A/C belt.
Step 6: Fit the new pulley into position and replace the A/C belt.
Step 7: Tighten the nut on the center of the pulley and the adjustment bolt. Check your vehicle's manual in case you have to torque the nut and bolt according to the manufacturer's specifications.
Step 8: Test your installation by turning up your air conditioning. If there is still a squealing noise, turn off your engine again and readjust the pulley and belt until the air conditioning works properly.