Car AC Makes Noise When Turned On – Reasons and Ways Out

Car AC makes noise when turned on issues do not offer the much-needed comfort during hot summer drives. These sounds can range from rattling to squealing noises due to underlying issues such as loose or worn-out belts.

Car AC Makes Noise When Turned On Solved

Continue reading this article as we will examine the common reasons behind your car AC making noises when turned on and the solutions to resolve the issue.

What Causes Your Car AC To Make Noise When Turned On?

What causes your car AC to make noise when turned on includes loose serpentine belts, a faulty AC compressor, or debris in the system. Further, a clogged or dirty air filter, malfunctioning blower motor, or a damaged fan belt can strain the AC system, could result in unusual knocking noises.

Below are the various reasons your car’s air conditioning system makes noise when activated:

  • Worn Out or Misaligned Drive Belt

A worn-out, misaligned serpentine belt remains one of the primary culprits behind the noise coming from the car AC unit. The AC compressor belt connected to the engine’s crankshaft drives the car’s air conditioner. This belt can become stretched, worn, misaligned, or develop cracks over time.

As such, when the belt slips or loses sufficient tension, it generates squealing or screeching noises when you turn on your AC due to slipping or rubbing against other components.

  • Faulty Car AC Compressor

A failing AC compressor can also contribute to the rattling noises you hear when you engage your car’s AC. The compressor is a vital component of car AC that helps pressurize and circulate the refrigerant throughout the system, maintaining the desired cooling effect.

Common compressor problems include worn-out bearings, loose or damaged components, or a failing ac compressor clutch assembly. Thus, if the compressor bearings get worn out or the compressor clutch becomes damaged, it can result in grinding or clicking noises when operating.

  • Obstruction in the AC System

Sometimes, debris or obstructions can find their way into the AC system, causing the whining noise when AC is on in car. Leaves, twigs, or other foreign objects may get trapped in the blower motor or the vents, causing disruptions in airflow.

Causes of Car AC Makes Noise

As a result, the accumulated debris or foreign objects causes obstructions, resulting in rattling or buzzing noises as air passes through the AC components. These noise levels may increase over time as the car air conditioner strains to function optimally.

  • Refrigerant Issues

Insufficient or contaminated refrigerant can cause your vehicle’s air conditioning system to work harder, thus making noises. Leaks in your vehicle’s refrigerant lines lead to low or inadequate refrigerant levels, increasing noise output. Moreover, if the refrigerant leaks near moving parts or the compressor, it can create unusual sounds or vibrating noise when the car ac is on.

Further, air or moisture in the system can result in a gurgling or buzzing noise. Overcharged systems can also generate noise due to excessive pressure within the system.

  • Clogged Air Filters and Condensers

Clogged air filters can lead to restricted airflow and cause the air conditioning system to strain, resulting in unusual noises. Over time, the cabin air filter can become blocked with dust, dirt, and debris. This eventually impairs its efficiency. Consequently, the car AC makes hissing noise when turned on.

The AC condenser is often situated at the front of the vehicle and helps dissipate heat from the refrigerant. On prolonged usage, the condenser can accumulate dirt, debris, or road grime, obstructing airflow and reducing efficiency. This restriction can cause the system to work harder, increasing noise levels.

  • Damaged or Loose AC Ducts

Damaged or improperly secured AC ducts can result in rattling or whistling sounds when you turn on the AC. The ductwork directs airflow throughout the vehicle by carrying the cooled air from the AC system to the cabin vents inside the car.

The ductwork can become damaged or loose over time, producing rattling or whistling noises when you activate your car’s AC. Damaged ducts can result from wear and tear, improper installation, sealing, or accidents. Vibrations from the blower motor or airflow can exacerbate these sounds.

  • Fan or Blower Motor Troubles

The blower motor helps push air through the vents and into the cabin. The AC system uses fans or blower motors to circulate air through the vents. If these components develop mechanical problems such as worn bearings, damaged fan blades, or debris accumulation, they can create rattling, squeaking, or humming sounds during operation.

  • Expansion Valve or Orifice Tube Problems

The expansion valve balances the flow of refrigerant into the evaporator coil in the AC system. If the valve malfunctions or becomes clogged, it can disrupt the refrigerant flow, causing the AC system to operate abnormally. This often results in unusual noises, such as hissing or gurgling sounds.

  • Electrical or Mounting Issues

Electrical problems can also contribute to AC noise. Faulty wiring, loose connections, or issues with relays or switches can cause intermittent or constant humming or clicking noises when you turn on the AC.

The AC system components are typically mounted using rubber or foam isolators to dampen vibrations. If these mountings deteriorate or become damaged, it can cause increased noise levels as vibrations are transmitted more effectively.

What Are the Ways to Fix a Noisy Car AC When You Turn It On?

The effective ways to fix a noisy car AC when you turn it on include replacing a worn-out belt or repairing a faulty AC compressor. Cleaning the AC system, tightening ducts, and practicing regular maintenance can also help eliminate noise and restore a peaceful driving environment.

  • Belt Adjustment or Replacement

A loose or worn-out AC compressor belt can cause noises when you activate your car’s AC. To fix this issue, start by inspecting the belt for signs of wear, cracks, or looseness. You can adjust the tension using the appropriate tensioning mechanism if it appears loose. Refer to your car’s manual for specific instructions.

If the adjustment doesn’t resolve the issue, you may need to replace the belt with a new one. Install a new belt of the correct size and tighten it according to the manufacturer’s specifications. This should eliminate any squealing or screeching noises caused by the faulty belt.

  • AC Compressor Repair or Replacement

If your car’s AC compressor has been damaged or has faulty internal components, particularly the compressor clutch, you may need to repair or replace the damaged components. In most cases, vehicle owners best leave the task to a qualified technician who can properly diagnose the issue and carry out the necessary repairs or replacements. This is because it requires specialized knowledge and tools.

Fixing Car AC Makes Noise When Turned On

So, attempting to repair or replace the AC compressor yourself may get challenging, so it’s best to seek professional assistance. A functioning AC compressor will ensure smooth and quiet operation of the AC system.

  • Clean the AC System

Cleaning the AC system and removing any obstructions can help eliminate the unsettling noises when you engage your car AC. To clean the system, start by disconnecting the battery for safety. Then, remove the cabin air filter and inspect it for any debris or obstructions. Inspect the air intake and vents for any visible debris. Also, clean or replace the filter as needed.

Then, use compressed air or a vacuum cleaner to remove dirt or foreign objects. It’s best to consult a professional automotive technician for a thorough cleaning and inspection and to prevent further noise issues.

  • Check and Tighten AC Ducts

Loose or damaged AC ducts can contribute to the loud noise in the system. Carefully inspect the ducts for any signs of damage, loose connections, or misalignment. Secure any loose connections and ensure all ducts are properly aligned.

If you detect significant damages, consider replacing the ducts with new ones to eliminate the noise effectively. You may require professional assistance for complex duct repairs or replacements.

  • Check for Other Loose or Damaged Components

Loose or damaged components within the AC system can promote hissing sounds when the AC gets turned on. As such, check for loose screws, bolts, or brackets around the AC components, such as the compressor, condenser, or evaporator.

Tighten any loose connections and change any damaged components as needed. Additionally, inspect the fan blades for any damage or debris accumulation, which can cause loud fan noise when AC is on in car. Cleaning or replacing the fan blades can help eliminate the noise.

  • Regular Maintenance and Filter Replacement

Routine maintenance remains crucial to maintain your car’s AC system. Regularly inspect and replace the cabin air filter to ensure proper airflow and prevent dirt and dust from entering the system. Additionally, follow the manufacturer’s recommended maintenance schedule to have your air conditioning system inspected and serviced by an expert.

Car Filter Replacement

For instance, they will check the refrigerant levels, evacuate and recharge the system, and ensure it is contaminant-free. Above all, this will help identify and address potential issues before they cause noise or other problems.


– What Are the Issues Encountered With a Car’s AC Evaporator Coil?

The issues encountered with a car’s AC evaporator coil include refrigerant leaks, coil freezing, reduced cooling performance, airflow blockages, and potential mold or mildew growth. These problems can result in insufficient cooling, unpleasant odors, and potential damage to the overall air conditioning system.

Regular maintenance and prompt repair of any issues can ensure the proper functioning of the car’s AC evaporator coil.

Car AC Makes Noise When Turned On

Can the Same Solutions for Speakers Making Noise be Applied to a Car AC Making Noise?

When it comes to addressing the reasons for speakers making noise and a car AC making noise, the same troubleshooting solutions may not be applicable. While speaker issues usually involve loose connections or damaged wires, a car AC noise can stem from a faulty compressor or a refrigerant leak. Different problems call for different solutions, highlighting the importance of seeking expert advice for each specific scenario.


A noisy car AC, when turned on, can disrupt your driving experience and indicate underlying issues within your vehicle’s air conditioning system. By understanding the common reasons behind these noises and implementing effective fixes, you can restore your car’s AC’s quiet and efficient operation.

Let’s go over some of the vital points we mentioned in this article:

  • Worn-out or misaligned drive belts and faulty AC compressors are the primary culprits behind the noise from your car’s AC system.
  • The other reasons your car’s air conditioner may make noise when activated include debris in the system, a clogged or dirty air filter, a malfunctioning blower motor, or a damaged fan belt, among others.
  • The effective ways to address the issue when your car’s AC produces unusual noises upon activation include replacing worn-out belts or repairing a faulty AC compressor. Cleaning the AC system and tightening ducts can also eliminate the disconcerting noise.
  • Remember that some repairs may require professional expertise, so do not hesitate to consult a qualified auto-technician. They will help identify the specific cause of the noise and recommend the necessary repairs or maintenance to resolve the issue.

Regular AC system maintenance and inspections will help prevent noise issues and ensure your car’s AC operates smoothly and quietly, providing optimal comfort during your drives.

5/5 - (14 votes)
Ran When Parked