What Causes the Engine Noise to Increase When the Air Conditioner is Turned On?
2 Answers
It is normal for the engine noise to increase when the air conditioner is turned on because the engine needs to drive the compressor, which raises the idle speed of the engine, resulting in louder engine noise. If the engine noise becomes noticeably louder, it could be due to reasons such as a dirty or stuck throttle valve, abnormal noise from the air conditioning pump, or improper tension of the compressor drive belt. The reasons for increased engine noise when the air conditioner is turned on are as follows: 1. Dirty or stuck throttle valve: When the air conditioner is activated, the compressor also starts working, and since the compressor is driven by the engine, turning on the air conditioner increases the engine load. This requires 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 vibration and abnormal noise, which becomes more noticeable when the air conditioner is turned on. 2. Abnormal noise from the air conditioning pump: There are two main causes for abnormal noise from the air conditioning pump—the electromagnetic clutch and the bearings inside the air conditioning pump. Noise from the electromagnetic clutch is mainly caused by wear, leading to increased gaps, while noise from the air conditioning pump bearings is due to insufficient lubrication. If these issues are not addressed promptly, they can cause the air conditioning pump to burn out, rendering the cooling system inoperative. 3. Improper tension of the compressor drive belt: If the drive belt is too loose, the electromagnetic clutch is prone to slipping; if the drive belt is too tight, the load on the electromagnetic clutch increases. Improper tension of the drive belt can cause abnormal noise in mild cases and damage to the air conditioning compressor in severe cases.
When the air conditioning is on, the engine noise increases. I often encounter this issue. As a veteran driver with over a decade of experience, I think there are several main reasons you should pay attention to. First, when the AC is turned on, the compressor kicks in, adding extra load to the engine—like running with a backpack—so the noise naturally increases. Second, the cooling fan might also start whirring, creating noise, especially in high summer temperatures. If the belt is loose or the compressor is aging, friction sounds can also worsen. Some cars are just designed this way and may not have major issues, but excessive noise can affect your driving mood. I suggest first checking if the AC belt is tight and seeing if the fan is dirty or obstructing airflow—these are simple fixes you can handle yourself. If it’s really bothering you, take it to a repair shop. Don’t ignore it, as delaying could lead to higher fuel consumption.
