How does the air conditioning system in a vehicle primarily cool the cabin?

The primary way the air conditioning system in a vehicle cools the cabin is through the process of compressing refrigerant. When the air conditioning system is activated, the compressor compresses the refrigerant, which starts in a gaseous state. This compression increases the pressure and temperature of the refrigerant.

Then, the high-pressure refrigerant flows to the condenser, where it releases heat and condenses into a liquid state. This liquid refrigerant then passes through an expansion valve, where it experiences a drop in pressure, causing it to evaporate and absorb heat from the cabin air. As this low-pressure refrigerant evaporates, it cools down and effectively absorbs heat from the surrounding air, resulting in cool air being blown into the cabin.

The other options describe processes or components that do not contribute to the cooling effect of the air conditioning system. Circulating warm air does not cool the cabin; instead, it would raise the cabin temperature. Engine coolant is used for cooling the engine and is not involved in the air conditioning system. Expelling carbon dioxide is unrelated to the cabin cooling process and does not contribute to air conditioning. Thus, understanding the role of refrigerant compression is key to grasping how automotive air conditioning systems function.