What are the functions of a car air conditioner?

[McJuliet]

The functions of a car air conditioner are: 1. To achieve a cooling effect through the continuous phase change cycle of the refrigerant; 2. To remove dust, odors, smoke, and toxic gases from the air inside the car, making the air fresher, and to humidify the air inside the car, increasing the relative humidity; 3. To use the engine coolant, waste heat, or heat generated by a burner as a heat source for heating, which is then heated by the heater and blown into the car by the blower, raising the temperature of the air at the vents to achieve heating; 4. To draw in fresh air from outside for ventilation and air exchange, which also helps prevent fogging on the windows.