Why is there abnormal noise when turning on the AC button?

[VonNoah]

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.

[LeSilas]

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.

[NadiaRose]

I totally relate to the weird noises when turning on the AC. First, identify the sound location: rustling inside the cabin usually means leaves in the blower motor; sharp whistling from the engine bay indicates aging belt slippage. Recently while helping a neighbor inspect his car, I found his 3-year-unreplaced cabin air filter had a blower clogged with poplar fluff causing a humming noise. Compressor bearings lacking oil also produce periodic clicking sounds, especially noticeable during stop-start at traffic lights. Don’t overlook the radiator fan either – excessive bearing play makes it whine like an airplane propeller. The most cost-effective solution is a thorough spring cleaning of the AC system, particularly the hidden duct corners where debris and pebbles often accumulate.

[Bethany]

There are five or six possible reasons for noise when the air conditioning is turned on. A clicking sound when the electromagnetic clutch engages is normal. However, if it's a metal grinding noise, it's likely that the compressor bearing has dried out and worn out. The most bizarre case I've seen while repairing cars: a mouse wedged a walnut between the fan blades, making a sound like knocking on a wooden fish when started. A squeaky belt can be temporarily fixed by spraying some specialized silicone lubricant. Remember to turn off the AC immediately when you hear unusual noises to let the compressor rest. Otherwise, if the bearing breaks, repairing it may require removing the front bumper and headlight assembly, costing up to three or four thousand yuan. Regularly changing the air conditioning filter can prevent 80% of foreign object noises.

[DiKhloe]

Air conditioning noises can be categorized into high-frequency and low-frequency cases. High-pitched whistling may indicate excessive refrigerant pressure, requiring inspection of the expansion valve and condenser. Low-frequency rumbling is typically caused by worn blower bearings, with replacement costing around three to five hundred. Last week, there was a modified car case where the owner installed a substandard air conditioning system externally, with poorly secured piping causing whole-vehicle resonance when the compressor started. Another classic issue is excessive clearance in the compressor's electromagnetic clutch, producing mechanical impact sounds upon engagement. It's recommended to open the hood and listen after turning on the AC: noise near the windshield points to fan issues, while near the headlights indicates compressor problems. For older vehicles, priority should be given to checking belt tension.

[VanAugust]

AC Button Abnormal Noise Troubleshooting in Three Steps. First, identify the sound type: buzzing points to the blower motor, clicking may indicate relay failure, while clunking suggests compressor issues. Second, check mileage - for vehicles over 80,000 km, focus on compressor mount bushings; if aged, the gap can fit a pinky finger. Third, review maintenance records - if the cabin air filter hasn't been replaced in five years, there's an 80% chance the blower wheel is entangled with fibrous debris. Once during rainy AC use, a boiling-water gurgling sound turned out to be clogged condenser drain tube causing water accumulation. Crucial reminder: always monitor the coolant temperature gauge when abnormal noises occur to prevent compressor over-wear leading to cooling failure - tow truck fees during hot weather can exceed 400 yuan per incident.