From top to bottom, automotive air conditioners are mainly composed of blowers, evaporators, pressure switches, dryers, expansion valves, condensers, and the most source compressors. The operation process of this air-conditioning system is: heat dissipation, heat absorption, compression, throttling. The compressor absorbs the refrigerant gas from the evaporator and compresses it into high-temperature gas into the condenser. Due to the decrease in pressure and temperature, the refrigerant gas condenses Liquid, the refrigerant liquid with higher temperature and pressure passes through the expansion device, the volume becomes larger, the pressure and temperature drop sharply, and the expansion device is discharged as a mist (fine droplets). The refrigerant liquid in the evaporator becomes gaseous, absorbing the surrounding A lot of heat, the surrounding temperature decreases. The pressure switch on the condenser plays an important role in reducing the pressure and temperature during the heat dissipation process. The pressure switch has a high pressure switch and a low pressure switch. However, high-pressure switches are generally used in the refrigeration system of automobile air conditioners. When the refrigeration pressure is too high, the pressure switch automatically trips to cut off the power supply or the circuit of the condensing fan to enhance heat dissipation. It acts like a temperature control switch in the electrical appliance same. Make the whole refrigeration system run better and extend the service life of automobile air conditioners.