Refrigerant in a gas form is compressed by the A/C compressor which runs off a belt, compressing the gas into a high-pressure state. his refrigerant then enters a condenser – a heat exchanger normally placed in front of the radiator - where it changes state into a liquid. The refrigerant then enters a dryer where most of the moisture is removed from the liquid. he liquid is then pumped through an orifice tube which takes the refrigerant from high pressure to low pressure, changing its state into a cold gas. The cold refrigerant in its gas state then flows through an evaporator. The evaporator then works as a cross-flow heat exchanger, cooling air that is passed through the heat exchanger fins by an A/C fan and finally blown through and into the cabin. One downside of air conditioning is that the temperature of the air entering the cabin is completely dependent on the ambient air temperature outside. The evaporator can only produce a certain rate of heat exchange, meaning that you will be adjusting your A/C dials to keep the cabin at your desired temperature. This makes air conditioning an open-loop system in engineering terms, meaning that it endlessly takes an input, applies a process (like heating or cooling) and then produces an output from that process. Changes to an open-loop system have to be made manually, like having to adjust the knobs on the dashboard to the red or blue areas to search for the exact temperature that you want.