Why Does the Engine Sound Louder When the Car's Air Conditioning Is On?
3 Answers
There are several reasons why the engine sounds louder when the car's air conditioning is on: Air conditioning pump noise: Any issue with the electromagnetic clutch or the bearings inside the air conditioning pump can cause abnormal noise. Noise from the electromagnetic clutch is mainly due to wear, leading to increased clearance. Noise from the air conditioning pump bearings is primarily caused by a lack of lubricating oil. In severe cases, this can cause the air conditioning pump to burn out, rendering the cooling system inoperable. Dirty or stuck throttle valve: Turning on the air conditioning increases the engine load, requiring the engine to increase the throttle opening to allow more air intake. If the throttle valve has carbon buildup or is stuck, it can cause engine shaking and abnormal noise. Poor tension of the compressor drive belt: If the drive belt tension is incorrect, it can cause noise in mild cases and damage the air conditioning compressor in severe cases. The principle is that if the drive belt is too loose, the electromagnetic clutch will slip. If the drive belt is too tight, the load on the electromagnetic clutch will increase.
Every time the car's air conditioning is turned on and the engine noise increases, I believe it's due to the increased workload of the compressor. When the compressor starts, the engine needs to exert more effort to drive it, and the higher RPM naturally leads to increased noise, especially on hot days. If the belt is loose or worn, it will squeak, which can be quite noisy; the fan system speeding up for cooling will also produce a whooshing sound; and the compressor itself aging and becoming stuck is a common issue. I usually recommend checking the belt tension and identifying the source of the noise to pinpoint the problem; regularly changing the engine oil and maintaining the air filter can reduce the load. Neglecting these issues may lead to increased fuel consumption or even engine overheating—safety first.
From my personal driving experience, when the car's air conditioning is turned on, the engine roars loudly mainly because the compressor starts and increases the engine's load. The fan spins faster to dissipate heat, which also generates additional noise. If the drive belt is loose or cracked, it can produce a sharp squealing sound due to friction. A rusty compressor operating inefficiently can also contribute to the noise. During routine checks, you can try feeling the belt by hand to see if it's loose. Lack of maintenance over time in the air conditioning system can worsen the problem. It's recommended to check the compressor's condition every six months to avoid costly repairs later. On long summer trips, turning off the air conditioning occasionally to give the engine a break can help reduce noise issues.
