AC Compressor Clutch Noise [Noise Types & Causes]

The AC compressor clutch is a crucial part of the air conditioning system in your car. It is responsible for transforming engine energy and transferring it to the compressor. 

The clutch engages and starts spinning to transfer power when you turn on the air conditioning. However, it can suddenly start generating some annoying noise, which might indicate that there is a problem with the clutch. 

In this blog post, we will look into the various types of AC compressor clutch noise, their causes, and how to resolve the issue.

AC compressor clutch

What is an AC Compressor Clutch?

An AC compressor clutch is a small, circular device positioned at the front of the compressor. This component links and disconnects the AC compressor from the engine.

This mechanical device pushes cooled air through the system and pressurizes the entire A/C system to ensure an appropriate operation. 

When you switch on your air conditioning system, the compressor clutch engages, and this will enable the relay to give power to the compressor clutch.

During this process, the cycling pressure switch monitors the refrigerant pressure and sends a signal to the relay to cut off the compressor if the pressure becomes too high.

If the compressor clutch is damaged, your air conditioner will not stay cool for long. This is because a broken, malfunctioning, or worn compressor cannot adequately manage the flow of refrigerant in the A/C system to produce adequate amounts of cooling. 

The compressor, like the engine, has numerous moving parts, and noises are a common complaint when the clutch develops an issue. Let’s look at the different noises and their meaning.

Types of AC Compressor Clutch Noise

1. Screeching Noise

The high-pitched noise coming from the clutch on the AC compressor in a car is the screeching noise.

This sound usually indicates there is a problem with your car’s drive belt or serpentine belt. The serpentine belt moves the pulley at your air conditioner compressor, which pressurizes the refrigerant lines and allows cool air to enter your cabin. 

In order not to endanger the AC system in your car, it is important to repair the AC clutch as soon as you hear the sound. Therefore, you will need a professional to diagnose the issue accurately.

2. Buzzing Noise

This is another noise that comes from your AC compressor clutch. This happens when the Freon in your car is surplus.  

The air conditioner overcharges when too much Freon overflows into the intake port of the AC compressor. This will result in the air conditioner being unable to cool your car and also damage some components in the car.

The Solution to Buzzing Noise

Examine the cooling system for leaks and repair any that you find with the Freon leakage repair kit. If the leaking persists, contact a mechanic to repair the refrigerant.

3. Knocking Sound

This noise usually indicates internal damage, especially in piston-type compressors. However, before blaming a compressor for noise, always inspect the compressor installation.

This is because loose mounting, such as loose bolts, can cause knocking noises from the compressor area, which can be mistaken for internal compressor noise.

When you turn on the air conditioner, the loose pieces shake and make a racket. A cooling system blockage, which results in unequal pressure, can also induce this noise. 

How to Fix a Knocking Sound in Your AC Compressor Clutch

  1. Examine the shaky components of the AC compressor clutch and tighten the nuts. Additionally, add a thread-locking substance to the loose parts to prevent them from becoming loose again. It should usually resolve the issue.
  2. Check the cooling apparatus to see if the mounting bolts are the source of the problem. If the bolts are the issue, the nuts would be moving, indicating that they are loose. You can use a spanner to tighten the loose bolts and nuts. 

4. Hissing

This is another typical sound drivers notice from their car’s air conditioner, a hissing noise. The good news is that this does not usually indicate problems.

If you hear hissing after turning off your automobile, that’s just your car’s technique of equalizing pressure.

Activating the AC creates a high and a low-pressure side in your system. A refrigerant such as Freon flows between these two distinct sides, which are separated by either an expansion valve or an orifice tube.

When you turn off your automobile, the Freon in your AC compressor will travel from the high-pressure side to the lower-pressure side to equalize.

5. Rattling Noise

A faulty power pump pulley or a broken catalytic converter might cause this noise from the compressor clutch.

The compressor clutch generates the pressure that circulates the refrigerant throughout the air conditioner system.

Therefore, if the air conditioner pulley system is malfunctioning, you will hear the rattling sound in your compressor clutch.

How to Fix a Rattling Noise

  1. Replace the ac belt or compressor clutch and have an engineer inspect the refrigeration system to determine the root cause.
  2. Check to find out if the hose belt and fans are in place and that there is no external effect on the compressor.
  3. We advise you to lubricate your ac compressor with the prescribed oil or a blend of lubricants. The mixing ratio for oil mixes must match the prescribed ratio. This will guarantee that the oils well are balanced. When the oils need to be changed, do so. If your compressor has a specific port, add lubricants via it.

Common Cause of AC Compressor Clutch Noise

1. Worn or Damaged Bearing

 The bearing is responsible for allowing the clutch to spin freely, and if it becomes worn or damaged, it can cause the clutch to make a grinding or screeching noise. This can also happen if the bearing has been contaminated with debris or dirt.

2. Lack of Lubrication

The clutch relies on lubrication to operate smoothly, and if there is not enough lubrication, it can cause the clutch to make a noise. This can happen if the lubricant has become old or has been contaminated with debris.

3. Clutch Issues

The clutch can become worn or damaged over time, which can cause it to make noise. Installation or excessive heat can damage the clutch.

If you are experiencing AC compressor clutch noise, it is important to have the problem diagnosed by a professional.

They will be able to determine the cause of the noise and recommend the appropriate course of action. In some cases, the problem can be fixed by simply replacing the bearing or adding more lubrication.

However, in more severe cases, it may be necessary to replace the entire clutch.


What is the Purpose of an AC Compressor Clutch?

The AC compressor clutch transforms engine energy and sends it to the compressor. When you switch on the air conditioner, the clutch engages and begins spinning to transfer power.

Read: Bad ECU Ground Symptoms


 If your air conditioning system makes a loud noise when you turn it on, then the compressor clutch may be faulty.

There are several potential causes of AC compressor clutch noise, including worn or broken bearings, inadequate lubrication, and clutch-related issues.

If you’re experiencing this, it’s crucial that you get it evaluated by a mechanic if you are unable to identify the root cause of the noise.