The correct input and output signals are crucial to the realization of the function of the air conditioning control system. The input and output signals of this system are mainly as follows.

1. Power supply and grounding

The controller is connected to the car's power supply through the ignition switch and fuse, which prevents short circuit between the controller and the car body. The vehicle battery pack must not power the controller at any time as long as the vehicle starter switch is not turned on. Connect the ground wire (labeled: "analog ground") to all external sensors and motor drivers with position signal feedback on the controller. This analog ground must be separated from all other external grounds and may only be connected to the automotive ground on the controller's printed circuit board.

2. Interior temperature sensor

The controller is connected to a sensor inside the car to measure the air temperature inside the car. The sensor is an NTC (negative temperature coefficient) thermistor. When the interior sensor fails, the default value is 25C for the interior temperature.

3. Potentiometer position of the hybrid air door motor

The controller is connected to the mixing door motor to obtain the position feedback information of the motor and realize control of the motor. The mixing door motor is equipped with a potentiometer to measure the rotation angle of the motor output shaft. The linearity of this resistor must not exceed +2.5%. The potentiometer is connected to three places. One is connected to the positive pole of the power supply, one is grounded, and the third is connected to the potentiometer slide wire resistance contact, which sends the changing voltage signal (analog quantity) to the air conditioner controller.