What Causes the Abnormal Noise from Car Air Conditioning Fan Blades?
4 Answers
The causes of abnormal noise from car air conditioning fan blades are as follows: 1. Dirty air conditioning filter: A dirty air conditioning filter can cause excessive noise and abnormal sounds. The air conditioning filter should be replaced promptly. 2. Foreign objects: Debris inside the blower fan blades can lead to abnormal noise. You can first turn on the blower without starting the engine to see if the noise occurs. If the noise appears, it can be confirmed that the issue lies with the blower. 3. Worn clutch bearing: The abnormal noise may be caused by a worn clutch bearing inside the air conditioning pump, which increases engine noise after turning on the air conditioning. This component cannot be replaced separately; the entire air conditioning pump assembly needs to be replaced.
It's quite common for car air conditioner vents to make strange noises, mostly due to debris stuck in the blades. Last time I cleaned my car, I found small branches and dust accumulated around the air filter, which probably caused the blades to squeak when rotating. It could also be due to plastic aging and deformation causing the blades to rub against each other, especially in summer when high temperatures make the plastic more brittle. For self-inspection, you can use a flashlight to check the gaps in the vents. If there's any foreign object, gently remove it with tweezers. If the debris is stuck too tightly or the blades are bent, you'll need to disassemble the entire vent panel, a job best left to a car repair shop. Normally, closing the windows when parking can reduce dust entry, and regularly cleaning the air conditioner ducts is also very helpful.
I've encountered the issue of noisy AC fan blades twice. The first time it was a candy that fell in, making a crackling sound when rotating; the second time was clearly mechanical noise, a clunking sound. My suggestion is to first identify the type of sound: a crisp rattling noise usually indicates foreign objects, while a low grinding sound may point to insufficient lubrication in the fan blade bearings. If you want to handle it yourself, turn off the AC and unplug the power, then use a soft brush to clean the fan blades and check for any cracks or deformations. If the noise only occurs when the cold air is on, consider whether condensation has caused icing and adhesion. Some older cars may also produce idling noise due to worn motor shafts, in which case the entire fan assembly needs replacement. I clean the air vents weekly, and haven't had any issues for four years now.
There are basically three reasons for noisy air conditioner blades: something stuck, deformation, or motor failure. The most common issue is clogging from willow catkins and leaves, especially prevalent in spring. Last time during a car wash, the technician taught me a trick: spray some disinfectant spray into the air vents a few times, which can both eliminate odors and soften debris. If there's a "buzzing" sound accompanied by vibration, it's likely the motor bearings are failing. Never force open the blades yourself—the small plastic shaft is extremely fragile, and breaking it would cause more trouble. It's recommended to also check the position of the air filter during inspection, as a damaged filter can shed fragments inside. New cars during the break-in period might also produce slight noises, which usually resolve themselves after driving a thousand kilometers or so.
