Why does the car make noise when the air conditioning is turned on?
3 Answers
When the car's air conditioning is turned on and noise occurs, it usually comes from two sources: one is the sound from the blower inside the car, and the other is the sound from the engine belt or compressor. When there is a problem with the compressor's electromagnetic clutch, it can cause the compressor to make noise. Here are some additional details: 1. Due to the transition from low to high-speed rotation, the requirements for the electromagnetic clutch are very high, and most electromagnetic clutches are installed close to the ground. When the bearings inside the electromagnetic clutch are damaged, it can cause noise. 2. Excessive clearance between the electromagnetic clutch and the compressor, loose drive belt, or low compressor efficiency may reduce power generation, leading to insufficient generator voltage and resulting in abnormal noise. 3. If there are foreign objects or lack of oil inside the blower, or if the blower itself is severely worn, it can also cause abnormal noise. Additionally, if the air filter has not been replaced for a long time, there may be foreign objects in the air ducts that can produce noise.
My old car had the same issue last year, buzzing annoyingly when the AC was turned on. Later, a check revealed it was due to worn-out bearings in the AC compressor, causing imbalance and noise during operation. I also encountered a situation where leaves got tangled in the fan blades, making a whooshing sound like a tractor. I suggest you listen to where the noise is coming from: if it's a clicking sound from the dashboard, it might be a broken gear in the flap motor; a whistling sound from the front is likely abnormal refrigerant flow. Not fixing these parts in time could damage the entire system. I took mine straight to the repair shop for a lift check, and they found a water bottle cap stuck in the blower—removing it made everything quiet again.
The most common issue seen in repair shops is abnormal noises from the air conditioning system. A loose or slipping belt will produce a squealing sound, especially noticeable on rainy days. A metallic 'click' when the compressor clutch engages is normal, but continuous rattling noises definitely indicate bearing failure. Just the other day, a car had severe dashboard resonance when the AC was on—disassembly revealed aged evaporator bracket rubber mounts. If you notice reduced cooling performance accompanied by a hissing sound, promptly check for refrigerant leaks. Such problems are best left to professionals; using a stethoscope to pinpoint the fault is the reliable approach.
