AC Compressor Clutch Noise – Common Problems

AC Compressor Clutch Noise – Common Problems

It is common for car air conditioners to generate cold with low sounds. These noises are AC compressor clutch activation, mixed airflow, and switch doors.

Others are from the fan motor and pressure balancing when the engine is turned off.

But it becomes unnerving when the compressor clutch of a car air conditioner produces some unusual sounds.

AC compressor clutch noise causes and solutions

At this point, you should check the cause of the strange sound and fix the problem before it becomes complicated.

Please look at the typical car AC compressor clutch noises, causes, and solutions.

A Loud Screeching Noise

Screeching is the high-pitched noise emanating from the car’s AC compressor clutch.

AC compressor clutch releases a screeching sound due to fast alternating refrigerant pressure.

It is relatively prevalent in automobiles when the air conditioner fails. Accelerating AC makes the worst screeching noise.

Screeching sound from the car AC clutch frequently indicates a problem with your car’s AC drive belt or serpentine belt.

Dry blower motor bearings are another possible cause. The origin of such serpentine belt problems may include a damaged belt tensioner dislocated pulley system.

The driving system includes the pulley system.


  1. Use water on the belt: Spray water on the ac belt to reduce noise.
  2. Replace the belt: If water doesn’t fix it, Observe the belt for damages, and get a new one if the belt is damaged.
  3. Inspect the vehicle: Check to see if the car and not just the AC have any issues.
  4. Screeching emanating from the AC clutch is very dangerous to your car AC and should be fixed ASAP. Therefore, you’ll still need a professional to identify the problem correctly. But you may inspect your serpentine belt for symptoms of wear, such as cracks and rips or missing ribs facing the pulley, before taking your car in for servicing.


If you hear a hissing noise from your car’s air conditioner clutch when it shuts off, it signals trouble. There might be an issue with the AC, but it is not guaranteed.

The typical hissing sound of a car AC compressor clutch includes the one heard when a new car AC is turned on.

It is hard because the parts of the new AC are not yet adequately screwed.

Sometimes, if you hear hissing from the clutch after turning off your automobile, that’s just your car’s way of equalizing pressure.

Typically, the car ac compressor has both a high and a low-pressure part. A pressure regulator or an aperture tube separates them.

Turning on the air conditioner, Freon, the refrigerant flows between these two distinct parts.

When the car is turned off, the refrigerant travels from the high-pressure part of your AC compressor to the lower-pressure part. It moves to equalize the pressure.

Aside from these normal operations of the AC, hissing could indicate the need for consulting the expert if it occurs unusually.

A broken or loose fan belt is often implicated.


  1. Check the fan belt for any cut or looseness.
  2. Observe the hoses for any damages.
  3. Clean the AC belt.
  4. Finally, contact an expert to fix the problem.


Surplus Freon in your car’s air conditioner may cause a lot of noise in the compressor clutch.

It is identified when you hear a buzzing noise in the compressor while accelerating the car. It is also detected when you first turn on your car’s air conditioner.

Excess Freon overflows into the AC compressor intake port and causes overcharging of the air conditioner.

Your air conditioner will be unable to effectively cool your car, perhaps causing significant damage to your compressor clutch or other components.

It is how the buzzing noise is produced.


  1. First, check the user manual and use the guideline. Examine the cooling system for leakages and fix if there are any with the Freon leakage fixing kit.
  2. Consult an engineer to fix the refrigerant if leakage continues after this.

AC compressor clutch noise


Knocking is caused by loose mounting bolts of the compressor clutch or loosening any other bolt and nut parts of the air conditioner.

When you turn on the air conditioner, these loose parts will shake while producing a racket sound.

Knocking is also caused by a cooling system blockage, bringing non-equalized pressure. You may want to diagnose the cause of the knocking noise properly.

Turn on the car engine, open the hood, and observe the air conditioner compressor clutch.


A knocking or slapping noise in the automobile air conditioner compressor clutch is one of the most superficial noises to repair without the assistance of a professional.

  1. Observe the shaking components of the AC compressor clutch and tighten the nuts. Furthermore, add thread-locking substance to the loose parts to avoid getting loose again. It usually should fix the problem.
  2. Observe the cooling apparatus and see if mounting bolts are the problem. If the bolts are the problem, the nuts would be making movements showing they are loose. You can use a spanner to fasten the loose bolts and nuts. To permanently repair the mounting bolts, get a thread locking substance.


Car air conditioners place significant power demands on the engine.

Therefore rattling noise from the compressor clutch may arise from a weak power pump pulley and damaged catalytic converter.

Different sources connected to the power system can equally cause a rattling noise. The following are some more typical origins of rattling noise:

  1. Rattling noise is a sign of a damaged air conditioner compressor clutch. The compressor clutch produces the pressure that pumps the refrigerant through the air conditioner system. Frequent air conditioner use may create wear and tear on the compressor clutch. Therefore, the compressor clutch or the entire AC compressor may need to be replaced. This option is recommended, especially if your car’s AC is continuously running.
  2. If the air conditioner pulley system bearing is damaged, it can produce a rattling noise. Whenever the AC compressor kicks in, you can sense it.
  3. Disconnected belt, fan, or hose.
  4. Poor lubrication of the compressor clutch. Using the wrong oil mixture like universal oils would eventually cause damage to the compressor, which affects the clutches. The viscosity of universal oils is quite different from the recommended oils (mostly synthetic}. As a result, it is hard to procure a uniform mixing of universal oils and refrigerants. The consequence is abrasion due to suboptimal lubrication.
  5. The depreciating tensioner is another cause of rattling noise. A failing tensioner makes the AC compressor clutch lose.


The rattling noise is best fixed at the mechanics. If your car’s AC compressor clutch develops a rattling noise, you should consult one.

However, the following hacks can be performed using the user guide:

  1. Replace the ac belt or compressor clutch, and let the engineer check the refrigerating system to identify the real problem.
  2. Ensure the hose belt and fans are in place without any external impact on the compressor.
  3. It is recommended to use the specified lubricant or mixture of lubricants for the AC compressor clutch. For oil mixtures, the mixing ratio must align with the specified ratio. It will ensure the balancing of the oils. Change the oils when due. Add oils through the designated port in a compressor that has one. It will ensure that the required volume is added. Apply a few drops of lubricant to the compressor cylinder to lubricate the clutch. Purchase oils from certified dealers. Contact a mechanic for his opinion.
  4. Replace the compressor clutch if any above solutions cannot fix the noise.

Growling Noise

It can be detected when the AC compressor clutch is turned on or off.

If the compressor is engaged, the noise may be due to spoilage of the compressor’s internal bearings.

Wearing of compressor pulley bearings and clutch bearing are some common causes of growling if the compressor is disengaged.


Consult a mechanic or fix it with the user guide manual.

Banging Noise

It is caused by a leaking cooling system that may use the liquid refrigerant seeping into the AC compressor clutch.


Consult a mechanic.

Grinding Noise

Grinding is caused by degeneration of the AC’s weak pulley bearings, mainly if the noise emanates from the car’s front.

Other causes include worn-out belts, blockade of condenser oil flow, and loose or spoilt fan blades.


Contacting a technician is the best approach to resolve this.


The sound of a car’s air conditioner compressor clutch is prevalent. A majority of the noise oozing from an AC compressor clutch indicates that the AC is in crisis.

Diagnoses are pertinent so that fixing will be done. You can do these on your own, mainly if you are conversant with this noise.

But you are advised to consult a mechanical engineer for his expert opinion and possible solution. Otherwise, get a brand new AC compressor clutch.