How To Fix A Noisy Car A/C Compressor

How To Fix A Noisy Car AC Compressor

When you need to run errands or take a drive on a hot summer day, your car A/C compressor can be your saving grace. If not addressed promptly, a car A/C compressor malfunction can result in significant service costs. The solution to each sound is different and requires a different level of expertise. Scroll below to learn how to fix a noisy car A/C compressor.

Buzzing Noises

Your A/C compressor may be damaged if it makes a buzzing sound. This sound will be heard as soon as the car A/C is turned on. Excess levels of refrigerant or leakage of refrigerant are usually the causes of such a problem.

In order to resolve the refrigerant leak:

  • Make sure there are no leaks in the cooling system.
  • Fix the leak by using a Freon leakage repair kit and following the instructions.
  • A mechanic can diagnose the problem if the refrigerant leak continues.

Knocking Noises 

When your car A/C is running, you may hear knocking or clicking sounds. This may be caused by the mounting of a compressor part. These parts usually have loose mounting bolts. In order to resolve this issue:

  • Start your car’s engine.
  • Take a look at the cooling system by opening the hood and standing back.
  • If the mounting bolts are loose, you will notice the loose part moving or shaking.
  • You can fix the problem permanently by tightening the mounting bolts with the appropriately sized wrench and investing in a thread-locking compound.

Hissing Noises  

Hissing noises may indicate that something is wrong with the compressor or cooling system as a whole. Possible causes may include leaking refrigerant lines, internal valve leaks, or high pressure inside the compressor.

Therefore, if you hear a prolonged or intense hissing sound, the compressor may be malfunctioning. At that point, it would be advisable to call a mechanic as soon as possible.

Rattling Noises

You might be on the verge of a compressor failure if you hear a consistent rattling sound. Compressor damage is caused by a variety of factors. A belt may have worn out or the compressor clutch may need to be replaced.

Noisy and Constant Vibrations

The vibrations and noises your compressor makes may simply indicate that it needs relubricating. Leakage or low pressure in the compressor commonly causes the compressor to lack lubrication. Follow these steps to lubricate the compressor:

  • Make sure you have good-quality oil injectors and refrigerant oils.
  • Use a clear tube to suck oil from the bottle.
  • To remove air bubbles, jiggle the plunger once filled.
  • Make sure the A/C is set to maximum cooling before starting the car.
  • Follow the manufacturer’s instructions on how much oil to add to the cooling system. Half an ounce is usually sufficient.
  • The sound will disappear as the oil runs through the system.


It’s important to note that to keep a car and all its parts functioning properly, regular maintenance is a must. Any malfunction must be checked out immediately to maintain the safety of you and your vehicle.