November 03, 2022
7 Reasons Why Car Ac Making A Whistling Noise
Car Air Conditioner

Car Ac is one of the most comforting pieces and we all want it to work correctly but problems begin when you notice the car ac making a whistling noise.

When it comes to surviving the scorching concrete jungle, we all want our car air conditioners to work at their maximum capacity. However, one must understand that there isn’t an ice maker inside. The cold air produced by your car’s air conditioner is the outside hot air that has had hot gases removed through a multi-step process to make it cool.

The multi-step processes might sometimes slow down the AC or become home to foreign particles. One can expect noise from the car’s air conditioner in such cases. It is also essential to find out why the car ac is making a whistling noise and to control the effects one should visit a car mechanic. A whistling sound can be due to a minor problem like your air conditioner getting older, or there could be several other reasons behind it.

According to Research Gate, when the HVAC system was running at both low and high speeds, the noise levels were consistently higher (47.1 dBA–48.6 dBA) than the ambient noise (38.0 dBA–HVAC off). The following sounds are made by AC when there is a problem with it:

  • Hissing or whistling sound- Is your car ac making a whistling or hissing noise? Leaking refrigerant is the most common reason for the whistling sound.
  • Screeching sound- It is associated with problems relating to fan motors.
  • Banging Noise – This noise is related to the problem related to the air compressor.
  • Humming sound- This problem is associated with the defective contactor relay switch.
  • Rattling sound- This sound is due to loose sticks or dust in your system.

Even if you are aware of the potential meanings of certain noises, different issues can frequently result in the same kind of noise, making it necessary to see an expert in air conditioning to identify the problem.

Why Does My Car AC Make High-Pitched Noise?

When your air conditioner produces a loud noise, the return vents, which are in charge of supplying cool air to the evaporator coils, aren’t getting enough airflow. But there might be other reasons behind these high-pitched noises. Let’s find out about some of them.

1. Clogged filter

The clogged filter is one of the most common reasons behind the whistling sound. A filter gets clogged due to the dust and debris that gets stuck in the filter. The air can’t pass through a clogged filter properly. Clogged filters not just cause a whistling sound but also cause overheating problems.

2. Vacuum Leak

Air forces through a hose by the mechanism that regulates airflow between the mass airflow sensor and the engine. The hose leaks or becomes loose in the majority of situations. You will eventually hear the whistling sound coming from your car’s front.

3. Not enough Transmission Fluid

If your car has run out of transmission fluid and you still try to drive, it will make a troublesome sound. You must replace the transmission fluid to stop the noise if the transmission is intact. Solving this problem might cost you a good amount of money.

4. Window Seals have deteriorated.

Worn-out window seals are another frequent cause of whistling sounds in automobiles. The car produces a whistling sound when high-pressure air enters the tiny aperture. Adhesives are used to seal the windows of cars. Prolonged exposure to heat and cold can sometimes cause an adhesive to weaken. Small gaps could consequently develop in the seal. If your car has this problem, fixing it is easy and cheap. Find the worn-out seal and replace it with a fresh one.

5. A Problem With The Radiator Cap

One of the main reasons behind the whistling sound is that the coolant system gets too hot when in use. The radiator pressure cap removes excess heat from the overheated coolant. But sometimes, the cap may occasionally malfunction and let air through. This can be one of the reasons why you hear a whistling sound without knowing its origin.

6. Leakage in the breather tube

If the breather tube in your car starts to leak, you might hear whistling or hissing from the engine compartment. One must maintain the breather tube to keep the vehicle in a good position.

The issue won’t get worse right away. However, waiting too long can lead to more problems with your car, requiring expensive car air conditioning servicing. Therefore, if you hear the engine whistling, take quick action.

7. Old Body Panels

Many of you don’t know this, but the whistling sound is very common in old cars that have damaged bodies. When air flow deviates in a different direction, it generates a whistling sound when you drive.

When I Turn On My Car AC, It Makes A Screeching Noise
Screeching Noise while Turning on the AC

A screeching noise is a long, high noise that is very unpleasant to hear. The reason behind this sound is a cracked AC belt or fault in the AC compressor. Some other causes are:

1. Faulty Air Compressor

If you hear a high-pitched screeching sound, your compressor system is most likely affected by a motor issue. The following are the reasons why the compressor clutch fails.

  • Blown or faulty A/C Clutch Fuse.
  • Faulty Switches and wiring
  • A/C Clutch Relay Failure.
  • Low or high Refrigerant Charge
  • Control Head/Computer Failure

    2. Low Refrigerant Charge

If there is a hole or crack in your refrigerant line, then it will cause leakage. Due to this reason, the level of refrigerant becomes seriously low. When fluid leaks for a period, the level drops very low. In order to circulate enough refrigerant through the system to cool your room, the compressor must exert twice as much effort. Eventually, the compressor will jam up as a result of this.

3. Ineffective Parts

When you use your car AC all the time, the AC clutch becomes hard. Dust, oil, and moisture also contribute to wearing out the parts. With time, these components will wear out, and eventually, the clutch will fail.

4. Components not installed properly

The compressor clutch consists of many components. Some components might not be installed correctly. This could contribute to the squealing sound.

5. Dirt Coils

It is obvious that when you use any electrical appliance, there will eventually be a lot of dust and moisture. This build-up dust can block condenser coils. The system won’t let out heat if it remains long enough in the AC. This will cause overheating of the compressor and hence failing of the system.

Why Is My AC Whining?

If you hear the whining sound as soon as you turn on your car’s AC, then there is a probability that your AC compressor or your AC belt is failing. A cracked belt will not affect the engine’s operation, but you won’t get cold air. The belt will slip under the engine’s torque and shriek when it can no longer securely grip the pulleys. This shriek frequently has a high pitch and is audible. This is most likely the indication that a car ac service is required to check the AC belt.

How Do I Stop Whistling From My Car Air Conditioner?

It can be incredibly unsettling if your car’s air conditioning system suddenly makes strange noises while you’re driving, like whistling or screeching. These sounds signify that it’s time for a visit to a mechanic for car air conditioning service. Although it’s not always clear if an issue is serious or not, the good thing is that your air conditioning system will usually let you know when something is wrong. Let’s first examine the basic reasons why car ac making a whistling noise, and we’ll then understand tips to stop them.

The following might be the reason for the whistling sound:

Malpositioned Duct – One of the ducts under the dashboard might be loose if you have recently been in an accident or even had your automobile serviced. The vents are typically fitted into one another rather than bolted at each portion. The air may whistle as it passes across the gap if one of those vents shifts out of alignment.

Some obstruction in the airflow system due to dust and any foreign object can cause a whistling sound in the car AC.

Now that we know the reasons let’s understand how you can stop your air conditioner from whistling.

  1. Almost all the noises you hear are from the air that opposes static air pressure. You should check if the air filter is clean and if the ducts have no kinks or blends.
  2. If your car is old, take it for a service every once in a while.
  3. Make sure there is no loose bolt left in your car. Any loose bolt will make a troubling sound.


It is essential to find out why the car ac is making a whistling noise. Not just are these noises irritating, but they can also cause severe problems in the car. When your air conditioner seems out of order, such as making weird and troublesome noise, or there are some smells or power cuts during its use, it signals that something might be wrong with its system. Neglecting these minor problems might cost you in the future.

Different noises from the AC represent various problems. Suppose your AC is making a buzzing sound. That means there is too much freon in your system. On the other hand, a knocking or clicking sound from the AC means that some bolts are left loose. So, every noise indicates a different problem. Ignoring such a problem can also result in costly car air conditioner repairs. So, the sooner you grab the problem, the better it is for your car and your own pockets. Proper maintenance and regular car AC servicing are the best ways to take care of your air conditioner.

Tags: Air Conditioner Squealing Sound, Car Ac Problems,
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