Car air conditioning electronic thermostat principle circuit diagram

Car air conditioning electronic thermostat schematic diagram

The working principle of this circuit is that when the temperature inside the car increases, the resistance of the thermistor Rt becomes smaller, causing IC1-2 to output a high level. Due to the role of R4, it helps to form a hysteresis, accelerating the voltage comparator IC1 -2 flip speed. At the same time, the voltage comparator IC1-1 flips over, IC1-1 outputs a high level, and through the voltage dividing effect of R6 and R7, the 5V voltage is added to pin 2 of IC2, so that pins 3 and 5 of IC2 are connected. So pin 5 outputs about +12V voltage, connect the air conditioner clutch at both ends A and B, and LED2 lights up, indicating that the air conditioner is working. The temperature inside the car gradually drops. When the threshold is reached, the air conditioner stops working. When the compressor fails or the battery voltage is lower than 6V, pin 4 of the diagnostic terminal of IC2 outputs a 5V voltage and LED1 lights up.