Self-Detect 5 Kinds Of Car AC Noises: Causes & How To Fix It

Car AC Noise

In general, the car AC system is quite silent and should not make strange and weird noises. The unusual car AC noise shows underlying problems. It must be addressed otherwise ignoring signs can worsen the problem and even can stop the AC from working in the middle of the highway.

In this powerful article, you are going to self-diagnose the five kinds of car ac noises such as hissing, squealing, clicking, rattling, and buzzing noises and their causes and fixing.

Related Post: Car AC Smells Bad When First Turned ON

Car AC Noises

A car AC produces many types of noises below are the five kinds of car AC noises.

  1. Hissing Noise
  2. Squealing Noise
  3. Clicking Noise
  4. Rattling Noise Or Knocking Noise
  5. Buzzing Noise

1. Hissing Noise From Car AC

AC System
AC System

Car AC hissing noise also known as whistling noise, is a type of car AC noise. The car AC hissing noise is produced when you turn OFF your A/C. It is something like a whistling noise. But, be calm, don’t worry it’s not an issue. It is the car’s way to equalize pressure between the high and low-pressure lines of the air conditioner.

Whenever you turn OFF your Air Conditioner, the refrigerant flows from the high-pressure side to the low-pressure side of the air conditioning system, as a result, a hissing noise is heard.

Related Post: How Car Air Conditioner Works

2. Squealing Noise When AC Is Turned ON

Worn Belt
Worn Belt

The car AC squealing noise is a loud screeching type of noise. It is the most common air conditioner problem. The car AC squealing usually happens when you turn ON your AC, and a loud squealing noise is produced. It is a symptom that your drive belt is loose or expired.

A drive belt, also called a serpentine belt, connects the compressor with the engine. The drive belt turns the compressor, which pressurizes the refrigerant inside the compressor to make your car cool. A loose drive belt will not turn the compressor properly and will slip on the compressor pulley, causing a loud squealing noise.

Examine the drive belt with your hands by pushing or pulling it to check its looseness. Similarly, with continuous usage for a long time, the drive belt is subjected to wear and tear, which causes cracks or tears in the belt that gets the belt to slip, and a loud squealing noise is produced. So, better to replace the drive belt.

Related Post: 7 Basic Parts of Car AC System (With Pics) & Their Functions

3. Clicking Noise Under Hood When AC Is ON

Compressor Clutch, Pulley And Coil
Compressor Clutch, Pulley, And Coil

When you turn ON the AC in your car, you hear a low-volume clicking sound, which is normal, because the compressor clutch engages with the pulley, causing a clicking sound. But, if you hear a consistent rapid clicking sound, then this is a sign that there is a problem.

An AC clicking noise can be caused by many factors, such as a seized compressor, a jammed pulley, and a low refrigerant. These factors could turn on the compressor, then off, then on, then again off causing a repeated cycle of an on and off, which is heard as a clicking noise.

Related Post: How To Fix Car AC Compressor Clutch Not Engaging

4. Car AC Compressor Rattling Noise Or Knocking Noise

Compressor Loose Mounting Bolts
Compressor Loose Mounting Bolts

The car AC Knocking noise or rattling noise is the result of a loose part or faulty component. Whenever the Air Conditioner is started, loose parts (which are not tight enough) especially mounting bolts of air conditioner components will shake, and make a knocking noise.

A rattling or knocking noise may also be a symptom of a faulty compressor. AC increases the load on the engine and also causes rattling noise. Some of the factors of rattling or knocking noises are a badly worn clutch, stuck compressor pulley bearing, and damaged idler pulley.

A good way to figure out the loose part is to turn ON the A/C and stand back, inspect all parts and tighten the suspected loose part.

Related Post: 11 Reasons Your Car Air Conditioner Blows Cold Then Warm

5. Car AC Buzzing Noise

The car AC buzzing noise is a sign of overcharged refrigerant in the car air conditioner. When the AC refrigerant is overfilled, it sounds like a buzzing noise when you turn ON the AC. It happens mostly after servicing the air conditioning system.

Too much refrigerant may lead to component damage and also poor cooling performance. So, it is better to have a technician take out the extra refrigerant from the AC system.

Related Post: 7 Reasons Your Car Stalls/Shuts Off When AC Is Turned ON

Frequently Asked Questions (FAQs)

Is it OK to drive with a bad AC compressor?

No, it is not advisable to drive with a bad AC compressor. The compressor is an essential component of the air conditioning system, and without it, the system will not be able to function properly. Additionally, it can put undue strain on the engine, leading to reduced fuel efficiency and increased emissions.

How long should car AC last?

There is no definitive answer to this question as it depends on a number of factors, including the make and model of the car, the quality of the AC unit, how often it is used, and so on. However, in general, most car AC units should last for several years (around five to seven years) without any major issues. To help ensure longevity, it is important to have the system serviced regularly and to check for leaks or other potential problems.

How do I stop my air conditioner from making noise?


If your car’s air conditioner is making noise, there are a few things you can do to try to fix the issue. First, check If the noise is coming from the cabin of the car, then it is likely an issue with the blower motor. if the noise is coming from the engine bay. If it is, then the problem is likely with the compressor, then you can try lubricating the compressor with a special lubricant. If neither of these solutions works, then you may need to take your car to a mechanic to have the air conditioner checked out.


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