What Causes the Loud Noise When the Car Air Conditioner is Turned On?
4 Answers
Car air conditioner makes loud noise due to rapid cooling. When the air conditioner is in automatic operation mode, it automatically controls the air outlet mode and fan speed based on the set target. When the air conditioner starts, if there is a significant difference between the set target temperature and the actual temperature inside the car, the air conditioning system will automatically select the highest fan speed to achieve rapid cooling. At this time, the blower will produce a noticeable wind noise. This is the sound produced by the high-speed operation of the air conditioning system's blower and is a normal phenomenon. Solutions for the loud noise when the car air conditioner is turned on: Adjust the temperature setting switch/knob to change the set target temperature and reduce the difference with the actual temperature inside the car. Adjust the fan speed setting switch/knob to lower the fan speed, and switch the automatic control mode to manual mode.
My car's AC used to be noisy too, and later I found that the most common cause was dust accumulation on the blower fan, causing the blades to make a rumbling sound when rotating, especially during summer use. Another major reason could be wear and tear on the AC compressor or unstable refrigerant pressure, leading to a roaring or rattling noise during cooling. Loose belt systems may produce squeaking sounds, and lack of lubrication or aging bearings can also worsen the noise. If the fan motor is overloaded, the sound becomes higher, and neglecting cleaning might lead to burnout. After cleaning the fan, it became much quieter, but if it's a compressor issue, a professional shop should check the pressure or replace parts. Regularly preventing dust from entering the engine bay and cleaning the filter during seasonal changes can prevent issues. If the noise suddenly increases, don’t delay repairs to avoid minor faults escalating.
The air conditioner makes excessive noise when turned on, which usually stems from inadequate routine maintenance. Excessive dust accumulation on the fan blades creates significant wind resistance and noise during rotation; when the air filter is clogged, the fan is forced to accelerate, increasing the whooshing sound. Internal wear of the compressor or pressure fluctuations due to refrigerant leakage can also cause abnormal noises. When the belt ages and becomes loose, it produces constant squealing, wasting electricity and being annoying. My experience shows that regularly cleaning external debris from the air conditioning system and replacing the filter and lubricating the bearings every six months works quite well. Without maintenance, accumulated issues may cause the compressor to fail, making summer drives even more uncomfortable. Checking is simple: park and listen for the noise source—the fan is located below the steering wheel, and the compressor is beside the engine. Taking timely action saves money and brings peace of mind—don’t wait until the noise becomes unbearable to act.
If the car air conditioning suddenly becomes louder, it's most likely due to issues with the fan or compressor. Dust and debris accumulated on the fan blades can cause high noise during rotation; an aging compressor may produce squeaky sounds. A loose or worn belt can also increase noise. Try cleaning the fan yourself first. If the noise persists after cleaning, the compressor may be faulty and require inspection. Addressing the issue early can prevent cooling failure, ensuring safety and peace of mind.
