The air conditioning refrigeration system consists of compressor, condenser, liquid storage dryer, expansion valve, evaporator and blower. Each component is connected by a copper tube (or aluminum tube) and a high pressure rubber hose to a closed system.

When the refrigeration system works, the refrigerant circulates through the closed system in different states. There are four basic processes in each cycle:

1. Compression process: the compressor inhales the low-temperature and low-pressure refrigerant gas at the outlet of the evaporator, and compresses it into high-temperature and high-pressure gas to discharge the compressor.

2. Heat dissipation process: high temperature and high pressure superheated refrigerant gas enters the condenser. Due to the decrease of pressure and temperature, the refrigerant gas condenses into liquid and produces a lot of heat.

3. Throttling process: the refrigerant liquid with high temperature and pressure increases after the expansion device, and the pressure and temperature drops sharply, and the expansion device is discharged with a mist (tiny droplet).

4. Endothermic process: the vaporized refrigerant liquid enters the evaporator, so the boiling point of the refrigerant is much lower than the temperature in the evaporator, so the refrigerant liquid evaporates into a gas. In the process of evaporation, a large amount of the surrounding heat is absorbed, and then the refrigerant vapor of low temperature and low pressure enters the compressor. The above process is repeated over and over again to reduce the air temperature around the evaporator.

The functions of automatic air conditioning include automatic control of temperature and humidity in the car, automatic control of return air and air supply mode, operation mode and air change control. Electronic control unit will be according to the drivers or passengers through air conditioning set button on the control panel, automatic air-conditioning system running, and according to all kinds of sensor input signal, to supply air temperature and air speed adjustments in a timely manner, to keep the car's air environment the best state.