Car AC Compressor

The air conditioning compressor is the heart of the entire air conditioning system. Most air conditioners (AC) work the same basic way, whether they be a refrigerator in the kitchen or a cabin cooling system on a car.

How Your AC System Works

The compressor is usually driven by a belt from the engine's crankshaft. On some vehicles, it's driven from an electric motor instead. The compressor's center shaft spins and it acts like a pump, compressing liquid coolant (usually referred to as refrigerant or by its R-value).

The compressed coolant is sent through to the condenser (an object that looks like a radiator and is often mounted in front of your engine's radiator). The coolant enters the condenser and the air flow around it removes heat from the compressed gas coolant.

From the condenser, the gas returns to the compressor and reverts back to liquid form as it loses pressure. In most systems, it does this inside a special chamber often called a receiver, dryer, or accumulator (depending on its design). At this point it is very cold and passing air over it cools the air before it enters the passenger cabin.

The AC Compressor

So the circulatory system for the refrigerant all begins at the compressor. On most vehicles, the AC compressor will last the life of the vehicle so long as it is well-kept.

An AC compressor should be "exercised" regularly to keep it performing. Most manufacturers recommend that it be run at least monthly for about ten minutes or so. On many modern vehicles, the AC switches on when the defrost is activated in order to dry the air to prevent more frost. So the compressor may be getting used all year round.

When the AC compressor needs replacement, it is often a relatively straight forward affair that a competent home DIY mechanic can perform, though the compressors themselves are often expensive.

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