Why does the belt make a screeching noise when the air conditioning is turned on?
2 Answers
Because the contact surface between the belt and the pulley has become too smooth. Below is relevant information about car air conditioning: 1. Air conditioning layout: Different types of air conditioning systems have different layout methods. Currently, most cars widely use an integrated heating and cooling air conditioning system. Its layout involves assembling components such as the evaporator, heater radiator, centrifugal fan, and control mechanism together, collectively referred to as the air conditioning unit assembly. 2. Air conditioning components: Modern air conditioning systems consist of a refrigeration system, heating system, ventilation and air purification devices, and a control system. Car air conditioning generally includes components such as the compressor, electronically controlled clutch, condenser, evaporator, expansion valve, receiver-drier, pipes, condenser fan, vacuum solenoid valve, idle speed controller, and control system. Car air conditioning is divided into high-pressure and low-pressure pipelines. The high-pressure side includes the compressor output side, high-pressure pipelines, condenser, receiver-drier, and liquid pipelines; the low-pressure side includes the evaporator, accumulator, return pipelines, compressor input side, and compressor oil sump.
I once encountered this annoying issue when driving an old car - a sharp screeching sound from the belt whenever the AC was turned on, loud enough to be really irritating. This is usually caused by belt wear or looseness, especially during hot summer temperatures when the belt material softens, combined with the additional load from the AC compressor startup, making slippage and friction noise more likely. If not addressed promptly, it could damage the alternator or water pump, leading to much higher repair costs. I recommend first checking the belt tension and condition, tightening it yourself if necessary, but avoid over-tightening as that accelerates wear. For long-term prevention, regularly replace the belt - ideally inspect it every two years to avoid major losses from minor neglect. After all, the noise isn't just irritating; it signals potential risks that shouldn't be ignored.
