The evaporator temperature sensor is a negative temperature coefficient sensor installed on the metal fins of the evaporator in the air conditioner assembly. Its function is to detect the temperature of the surface of the evaporator, and input the detection result to the automatic air conditioning control unit, thereby adjusting the working time of the air conditioner. Normally, after turning on the air conditioner, the evaporator keeps cooling; when the temperature reaches the set value, a signal is sent and the compressor stops working. When it detects that the surface temperature of the evaporator is close to 0 degrees, it will automatically disconnect the compressor clutch, stop cooling, and avoid frost on the evaporator. When the temperature of the evaporator surface rises, it will automatically start the compressor to start cooling.