Why Is My Car Air Conditioner Making Noise?


When it’s hot and muggy outside, all you want your air conditioning to do is blast cold air in your face. You don’t want to hear your car's air conditioner making noise or malfunctioning. An unidentified noise in a vehicle is almost never a good thing.

If you’re asking yourself, “Why is my car air conditioner making noise?” you’re not alone. However, there are many reasons why your car’s air conditioner might make noise. It all depends on the noise it makes and what else is going on with the car.

If you’re not sure why your air conditioner is making noise, keep reading to learn more about what the potential cause (and solution) could be. You might find the issue simpler to fix than you thought.

11 Things that could cause the car air conditioner to make noises

As you look through the following reasons why your car air conditioner might be making noise, take notes as to what you hear when the air conditioner is on, or what other things may be happening. These are clues that can help you figure out what’s really going on.

Loose or damaged fan belts

A loose or damaged fan belt can make a terrible noise if you’re running your car’s air conditioner. Most fan belts are supple and soft when they’re new, so they ride easily without much noise. However, when those fan belts wear out or get damaged, they can become the squeaky wheel that needs greasing.

If you think you have a loose or damaged fan belt, be sure to turn the car off first. Then, wait until the engine has cooled down to visually and physically inspect the belt. If you see any signs of wear, it’s time for a new fan belt.

If you have continued problems with your fan belt, it’s worth taking your vehicle to your mechanic. There could be a separate reason why the fan belt is loosening or sustaining damage that may need a trained eye.

Worn-out compressor bearings

Bearings help everything go smoothly, but when they wear out, you can definitely tell. If you hear a consistent squealing noise and you’ve already checked your fan belt, it could be the bearings wearing out.

Most compressor bearings last about 10 years or so, but premature failure can occur. If this is the case, you should replace the bearings as soon as you can to avoid further damage to the compressor.

Blocked or dirty air conditioning condenser

Refrigerant makes a whole lot of difference when it comes to delivering cool air through your air conditioning vents.

If that refrigerant can’t pass through the condenser efficiently, however, you could have serious problems in addition to a noisy air conditioner.

One of the easiest ways to tell if you have an air conditioner condenser that’s blocked or dirty is a lack of cool air.

This can be difficult to determine if the temperature outside is particularly hot, but you should eventually feel the temperature drop as the condenser works.

If that’s not the case, it’s worth checking out the condenser to see what’s wrong. Pressure and flow can also help you to determine how your air conditioner condenser is operating.

Leaks in the air conditioning system

A refrigerant leak can easily lead to a hissing noise and loss of coolness in your air conditioner system. If you suspect you have a refrigerant leak, minimize the noise around you to see if you hear a hissing or high-pitched whistling coming from the engine bay.

Leaks in the refrigerant will also cause your air conditioner to become less effective. While most refrigerant leaks are caused due to age-related failure, they can also become punctured in certain instances. Check your air conditioning system for other compromised components if you have a refrigerant leak.

Debris in the air conditioning system

Clogging up the air conditioning system can certainly cause noise. Since the air is moving through the system at potentially high acceleration, any blockages can distort that air and cause noise.

If you are getting less airflow from one vent versus another, it could be because there’s debris in that one area.

If you live out in the country or haven’t driven your car lately, you might have a furry critter in your AC system. Sometimes small animals like field mice and rabbits will take up shelter in an abandoned vehicle, specifically in tight spots they can use for warmth.

Debris in your air conditioner system can also cause a smell depending on how long the debris has been there and what type of debris it is. If you notice a smell along with a noise when you run your car’s air conditioner, it might be time to take a closer look.

Broken or worn-out fan blades

If you hear a slight chopping noise when you turn on the air conditioner in your car, it could be that the fan blades are worn out or broken. These blades wear out over time, like every other feature on your vehicle.

Replacing broken or worn-out fan blades can be difficult. If you’re not sure how to replace them or don’t feel comfortable, it can be worth the cost of a mechanic visit to get the blades and the squealing sound fixed.

Broken or damaged fan clutch

You’ll notice as you work the air conditioner in your car that a fan will turn on and off to move cold air through your vehicle. Power is sent to the fan to kick on at certain intervals, which is noticeable by a surge of energy from the engine that makes it run at a slightly higher pitch.

However, if the fan fails to kick on because of a broken or damaged clutch, you won’t get the cold air you crave. If the fan can’t operate because of the clutch that gives it power, you won’t get any cold air in the cabin.

While you might be able to diagnose a broken or damaged fan clutch, it’s often best just to take your vehicle to the shop.

The technicians will have to remove the broken or damaged clutch and install a new one to fix the issue.

While you might be able to get away with not fixing the issue for a while, it’s not a good idea to leave it damaged.

Malfunctioning compressor

A malfunctioning air compressor can mean bad news if you’re trying to cool down. If you hear odd clunking noises or just aren’t sure what’s making noise, it could be time to replace your air conditioner compressor.

Air conditioner compressors are responsible for moving cold air through the system into the cabin of the vehicle. The compressor takes the refrigerant and circulates it to create a cooler atmosphere you can appreciate when it’s hot outside.

If the compressor isn’t moving cool air through the system, it could be an issue of electrical connection, a broken component, or simply a worn-out compressor. You’ll need to take a closer look at the compressor itself to see what’s really going on.

Damaged or worn-out pulleys

The air conditioner clutch and pulleys work together to engage the compressor and blast cold air into your vehicle. If the clutch engages but the pulleys don’t, then your compressor won’t ever get the power from the engine that it needs to cool you down.

Pulleys act as the coupler between the air conditioner clutch and the compressor. If these pulleys are damaged, they could cause a large clunking or another type of odd noise in the engine bay. The clutch could be trying to engage, but the pulley may not be fully seated to then bring power to the compressor.

Clogged air conditioning evaporator

Most air conditioner evaporators that make noise will emit a buzzing or squealing sound. This stems from the ice that’s formed on the coils within the unit. Fixing this issue means you’ll need to thaw that ice and remove it from the coils.

Thawing the built-up ice can either be done by turning the air conditioning itself off, turning the fan on, or inspecting the air filter. The coils within the air conditioner unit may freeze if there’s a particularly cold day, but they should easily thaw out as the temperature gets warmer.

Overcharged or undercharged refrigerant levels

Believe it or not, under or overcharging your refrigerant can lead to noises in your car’s air conditioner. It can also make it difficult for the system to work properly since there’s either too much or not enough refrigerant to cool you down.

Most undercharged air conditioner units will just blow warm air, but overcharged units can squeal. The abundance of pressure in the system pushes components to their maximum, depending on how overcharged the system is.

It’s often best to take your vehicle to a mechanic if you’re having issues with the refrigerant levels. Technicians can adjust the level to comply with the manufacturer’s specifications so your car air conditioner works properly.