Why is there abnormal noise when turning on the AC button?
2 Answers
When the air conditioner is turned on, abnormal noise from the engine area mainly has two causes: 1. Metal friction sound emitted when the compressor electromagnetic clutch engages. 2. Squeaking sound caused by excessive force on the air conditioner belt. Note: These two situations only occur when accelerating with the air conditioner on. The specific reasons are as follows: 1. Lack of refrigerant oil: Metal friction sound is emitted when the compressor electromagnetic clutch engages, usually due to insufficient refrigerant oil for lubrication inside the compressor. When refrigerant oil is lacking, the internal piston of the compressor does not receive adequate lubrication, resulting in metal friction sounds under the high pressure of the refrigerant. 2. Electromagnetic clutch failure: The electromagnetic clutch itself is faulty, with internal bearing damage causing abnormal noise, requiring compressor replacement.
Don't ignore strange noises when pressing the AC button. Last time I encountered this, it turned out the AC compressor belt was loose, producing a squealing sound like something slipping. The compressor itself might be faulty - worn bearings cause a humming noise. Fan motors can make scraping sounds if leaves/debris get stuck. Older cars often have loose compressor bracket screws that rattle on bumpy roads. The scariest is blocked AC lines - refrigerant flow creates loud cracking noises from excessive pressure. Immediately turn off AC, open windows, and drive to a repair shop. Mechanics use stethoscopes to pinpoint the source - compressor repairs can cost thousands.
