The typical temperature sensors used in the air conditioner is a thermistor. The temperature is measured by using the characteristic that its resistance changes with the temperature, and the electrical signal is then sent to the microcontroller through the sampling circuit to realize the temperature detection. Thermistors can be divided into Positive Temperature Coefficient (PTC) thermistors and Negative Temperature Coefficient (NTC) thermistors according to their different sensing characteristics. Among them, the resistance of NTC thermistor has a negative temperature coefficient, its resistance decreases with the rising of temperature; while the resistance of the PTC temperature sensors has a positive temperature coefficient, its resistance increases with the rising of temperature.