What is the primary function of an air compressor in a vehicle?

The primary function of an air compressor in a vehicle is to pump air into the storage tanks or reservoirs. This is especially crucial in vehicles that utilize air brake systems or pneumatic systems, where compressed air is essential for operating brakes, doors, and other components. The air compressor takes in ambient air and compresses it, sending it to the reservoirs where it is stored until needed. This ensures that the air pressure remains consistent and readily available for various operations within the vehicle.

Other functions suggested in the options, such as pumping fuel, cooling the engine, or recharging the battery, do not relate to the role of the air compressor, which is specifically designed for managing air pressure and not for fluid pumping, engine cooling, or electrical battery functions.