Compressors are positive-displacement pumps used within a vehicle’s air conditioning and refrigeration systems. Typically driven by the engine via a belt, they circulate refrigerant, increasing its pressure and temperature to facilitate the cooling process. Modern compressors frequently utilize variable displacement technology to optimize efficiency and cooling capacity based on demand. Key components include a piston, scroll, or rotary mechanism, along with internal check valves and a clutch for engagement/disengagement. Lubrication is critical, requiring specific refrigerant oil compatible with the system’s refrigerant type.