An air-conditioning compressor is a key component in a car’s air-con system. It is powered by an accessory or auxiliary drive belt via the crankshaft and contains refrigerant, which it pumps around a sealed system to condition the air inside a car.
How does air-con compressor work?
Air is drawn from outside the car (or inside if the ventilation is set to recirc), through the radiator and condenser, and is blown over the evaporator (a type of radiator) by the ventilation fan and into the car’s interior.
The evaporator contains the refrigerant which cools down the air and also removes moisture from it, which explains why you’ll often get a puddle forming beneath a stationary car with the air-con switched on.
The refrigerant then flows through to the compressor, which pumps the refrigerant to the condensor as a vapour before it turns into a liquid again.
Although air-conditioning is an energy-intensive process, and increases the amount of fuel a car uses, modern systems are efficient.
Many drivers believe that air-con can only be used to cool the car, and therefore use it only during the warmer months of the year.
In fact not using the air-con at least once a week can harm it, because the refrigerant acts as a lubricant for the system’s seals and gaskets.
So we recommend switching on the air-con and turning up the heat on a regular basis during the winter - the dehumidified air generated by air-con is also excellent for clearing steamed-up windows.
Air-con not working?
Over time the refrigerant can leak from the system and needs to be topped up or entirely replaced. Your local garage should be able to check the car’s system’s pressure and refill it.
However, it’s important to make sure there aren’t any leaks from seals, gaskets or the compressor itself before it’s refilled, or you’ll be wasting your money.