The working principle of the automobile air conditioning refrigeration system: the sensor first detects the temperature inside the car and the temperature of the engine coolant, and then transmits the signal to the four main components: the compressor, condenser, expansion valve and evaporator, and forms a closed circulation system through pipelines, so that the refrigerant absorbs the heat energy in the car when it is converted from liquid to gas, and refrigeration is achieved in this way.

The working principle of automobile air conditioning is mainly divided into the following four processes:
1. Compression process of automobile air conditioning working principle: The compressor sucks in the low-temperature and low-pressure refrigerant gas at the outlet of the evaporator, compresses it into high-temperature and high-pressure gas and discharges it from the compressor;
2. Heat dissipation process of automobile air conditioning working principle: The high-temperature and high-pressure superheated refrigerant gas enters the condenser. Due to the decrease in pressure and temperature, the refrigerant gas condenses into liquid and discharges a large amount of heat;
3. Throttling process of automobile air conditioning working principle: The refrigerant liquid with high temperature and pressure increases in volume after passing through the expansion device, and the pressure and temperature drop sharply, and it is discharged from the expansion device in the form of mist (fine droplets);
4. Heat absorption process of automobile air conditioning working principle: The mist refrigerant liquid enters the evaporator. Since the boiling point of the refrigerant is much lower than the temperature in the evaporator at this time, the refrigerant liquid evaporates into gas. During the evaporation process, a large amount of surrounding heat is absorbed, and then the low-temperature and low-pressure refrigerant vapor enters the compressor again. In this working principle process, it is repeated over and over again, so as to achieve the purpose of reducing the air temperature around the evaporator.

Functions of car air conditioners:
1. Ventilation function. The purpose is to maintain normal ventilation in the vehicle, inject new air into the room, and eliminate the impact of gases such as carbon dioxide on the driver and passengers;
2. Heating function. Especially in cold weather, car air conditioners can inject warm air into the room to achieve the effect of heating and dehumidification;
3. Refrigeration function. In summer, the temperature in the car is relatively high and stuffy. At this time, the car air conditioner can lower the temperature in the car to make passengers feel more comfortable;
4. Air purification function. The car air conditioner will filter the air introduced into the car, eliminate harmful gases in the car, and ensure the cleanliness and freshness of the air;
5. Control function. The car air conditioner can not only control the cooling and heating systems, but also manipulate the temperature circulation method of the air in the car.