What Causes the Car AC Compressor to Make Noise When Turned On?

[AlexanderLee]

It may be caused by excessive engagement gap of the electromagnetic clutch. Below is relevant information about automotive air conditioning: 1. Introduction to Automotive Air Conditioning: The automotive air conditioning system consists of a compressor, condenser, throttle element, evaporator, fan, and necessary control components, designed to regulate the temperature and humidity inside the vehicle, providing a comfortable environment for the driver. 2. Working Principle: When the compressor operates, it draws in low-temperature, low-pressure gaseous refrigerant from the evaporator. After compression, the temperature and pressure of the refrigerant increase, and it is sent to the condenser. Inside the condenser, the high-temperature, high-pressure gaseous refrigerant transfers heat to the outside air passing through the condenser, causing it to liquefy into a liquid. The liquid refrigerant then flows through the throttle device, where its temperature and pressure decrease, and it enters the evaporator. Inside the evaporator, the low-temperature, low-pressure liquid refrigerant absorbs heat from the cabin air passing through the evaporator, causing it to evaporate into a gas. The gas is then drawn into the compressor again for the next cycle.

[LeClara]

When I first encountered this situation, I thought the air conditioning was broken. In fact, there are quite a few reasons for compressor noise. The most common one is a loose belt. When the air conditioning is turned on, the compressor load increases, and the loose belt will make a squeaking sound. It could also be due to internal bearing wear in the compressor, causing a humming or friction noise when it rotates. Too much or too little refrigerant is also problematic, as abnormal pressure can cause the compressor to surge and make noise. There's also the issue of the clutch not engaging smoothly, which can produce a clicking sound at startup. I first checked the belt tension myself, and when I found no issue, I promptly went to the repair shop. The mechanic said such noises shouldn't be ignored—minor cases can affect cooling, while severe ones can damage the compressor, leading to thousands in repair costs. My advice is not to tough it out when you hear unusual noises; timely inspection and repair are the best course of action.

[FrankRose]

Compressor making noise? This is a core issue in the air conditioning system. Let's break it down: Insufficient tension in the drive belt is the primary cause, with loose belts squealing under heavy load; aging clutch leading to poor engagement produces a gear-grinding-like clatter; lack of lubrication or wear in compressor bearings results in metallic friction noises during rotation; and an imbalance in refrigerant levels is equally critical, as both high and low pressure states can cause abnormal vibrations and noises from the compressor. Last time I encountered this, I noticed a clear drop in cooling efficiency and increased fuel consumption. My advice to fellow car owners: first, check the belt's condition and tension; second, test the refrigerant pressure—both can be done DIY. If these don't resolve the issue, take it straight to a professional. Never delay repairs to save money.

[CamilleFitz]

The noise when turning on the AC is mostly the compressor protesting. I've encountered this three times: the first was due to a loose belt, the second was low refrigerant, and the third and most troublesome was a failed bearing. Belt issues are easy to fix—just spend a few dozen bucks to tighten it. Abnormal refrigerant levels make the compressor work harder, producing a dull humming sound, which can be resolved by topping up the refrigerant. If you hear a metallic grinding noise, it's likely the bearing is gone, and the only solution is to replace the part. I recommend turning off the AC and pulling over immediately upon hearing unusual noises, as continued operation could burn out the compressor. Average car owners can check if the belt is loose themselves, but for other issues, it's best to consult a professional mechanic.