Reasons for Loud Noise When Car Fan Turns On
2 Answers
When a car fan produces abnormal noise upon activation, it is typically caused by deformed fan blades, motor damage, or clogged and dirty air conditioning systems. The fan automatically turns on when the coolant temperature exceeds 95°C. Deformed fan blades will generate excessive noise during rotation, while a damaged fan motor can also cause irregular fan speed, leading to abnormal sounds. Dirt and blockages in the air conditioning system can result in excessive airflow noise. It is recommended to clean the air conditioning system. Generally, the cabin air filter should be replaced every 10,000-20,000 kilometers. If the vehicle operates in a dusty environment, the replacement interval should be shortened. The air conditioning system's pipes may develop mold or accumulate debris over prolonged use, so a thorough cleaning is advised every 30,000-40,000 kilometers. A car's air conditioning system primarily consists of a refrigeration system, heating system, air delivery system, control system, and air purification system. The refrigeration system includes components such as the evaporator, air conditioning compressor, condenser, liquid storage tank, expansion valve, and high/low-pressure pipelines. The heating system mainly comprises a heater core, water valve, and blower motor. Its working principle involves receiving signals from various sensors (detecting cabin temperature, evaporator temperature, engine coolant temperature, etc.) to output control signals. These signals regulate the radiator fan, condenser fan, compressor clutch, blower motor, and air control motor to achieve automatic temperature control inside the vehicle.
I've been driving for years and it's not uncommon to encounter a roaring noise when the fan kicks in. The most common culprit is dust, leaves, or small stones accumulated on the fan blades, causing friction and noise during rotation. Aging bearings are another frequent issue—after years of use, increased bearing friction makes the motor run less smoothly, especially producing louder noises during cold starts. Additionally, loose wiring connections can exacerbate vibrations; last time I tightened the connections myself, the noise significantly reduced. Improperly secured fans or cracked casings can also cause abnormal vibrations. It's advisable to regularly open the engine hood to clean the fan area. If the noise persists after cleaning, it's time to visit a shop to check the bearings or replace parts. Don’t delay too long—it affects both your mood and driving comfort.
