AC compressors are positive-displacement pumps integral to a vehicle’s air conditioning system, typically driven by the engine via a belt or, increasingly, powered electrically. These units compress refrigerant gas, increasing its temperature and pressure to facilitate the cooling process within the evaporator. Modern compressors utilize variable displacement technology to optimize efficiency and cooling capacity based on demand. Key components include a reciprocating piston, rotary vane, or scroll mechanism, coupled with an electromagnetic clutch or variable control valve. Proper function relies on maintaining sealed internal pressures and lubrication via the refrigerant oil.