Overview of Major Parts
Overview of Construction, Movement and Control of Major Parts of Automatic Air Conditioner SystemAutomatic Air Conditioner Control Unit
Equipped with the built-in micro-computer, this control unit operates on signals from sensors and input signals from switches to offer total control of the blower fan, and actuators used for the mode door, intake door and air mix door.
Its self-diagnosis function enables quicker access to a failed part and its more accurate troubleshooting.
In Car Sensor
It is a sensor used for detecting room temperature of a vehicle. This sensor converts a given room temperature into a resistance value before entering the data to the automatic air conditioner control unit.
This in car sensor unites the power driven aspirator and the motor fan so that a small amount of room air may be constantly fed to the sensor.
This sensor is provided on the right side of meter cluster.
Ambient Sensor
This sensor is used for detecting temperature outside the vehicle. It converts a given outside air temperature into a resistance value before entering the data to the automatic air conditioner control unit.
Thermal effects from the condenser and radiator during idling after a run can be measured and offset the automatic amplifier.
This sensor is provided on the side plate situated at upper right side of the condenser.
Duct Sensor
The duct sensor is the sensor to detect temperature change of the side of evaporator blower coming by fresh recirculation of intake door or "on" "off" of compressor.
The temperature is converted to resistant rate.
And it works as thermostat to control to prevent freezing of evaporator.
This sensor is installed in the upper case of evaporator.
Sun Sensor
It is a photodiode used for detecting quantity of solar radiation. This sensor converts the offset signal generated by changes in the interior temperature (which results from fluctuations in solar radiation) into photoelectric current to enter into the automatic air conditioner control unit.
This sensor is provided at top of the center cluster upper.
Power Transistor
Receiving base current from the automatic air conditioner control unit, the power transistor implements stage-less speed change of the blower fan motor. This transistor is provided on the evaporator.
Max Hi Relay
This relay turned on or off by the signal from the automatic air conditioner control unit. As the Max Hi relay is turned on, supply voltage is directly fed to the blower fan motor to select the Max Hi mode.
Actuator
The actuators are power driven type containing a small motor. Receiving output current from the automatic air conditioner control unit, actuators drive the heater and blower unit mode doors.
Actuators consist of the mode actuator used for switching the mode (blow port selection), the mix actuator used for changing aperture of the air mix door, the intake actuator used for switching the intake mode(fresh air/interior air) actuator.
The actuator changes the motor speed using the gear and drives each door rotating the output axis united with the sliding contact.
The mode and mix actuators are common actuators with the built-in potentiometer. For the intake actuator, the contact switch type is selected.
The potentiometer is a register assembled to the printed circuit board of the mix and mode actuators. It detects the air mix door position specified by rotation of the output axis as a ratio of the variable terminal (VM) voltage against the reference voltage (VDD: 5 V), then signals the value to the automatic air conditioner control unit.
Movement of Mix Actuator
Position of the air mix door is determined by the controller on the automatic air conditioner control unit.
As the heat or cool side of the controller is grounded, the transistor on the driver is activated and, thus, the motor rotation is turned on. The sliding contact connected to the motor sends the position detection signal from the potentiometer to the automatic air conditioner control unit. As the set temperature and interior temperature are balanced, the controller returns to the neutral and the motor rotation is stopped.
Movement of Mode Actuator
As target position of the mode door is decided on the controller of the control unit, the control unit reads the position detection signal from the actuator to select the clockwise or counter clockwise motor rotation direction.
Grounding the controller VENT or DEF side after the direction selection activates the transistor on the driver, thus turning on the motor rotation. Accompanying the motor rotation, the sliding contact rotates, too. When the target position is reached, the controller on the control unit returns to the neutral and the motor stops.
Movement of Intake Actuator
The controller on the automatic heater/air conditioner control unit selects an intake mode to be used.
As the Terminal No. 5 C-33 is grounded via the sliding contact on the terminal plate, the transistor on the driver is activated, thus turning on the motor rotation. Then, accompanying move of the motor, the sliding contact rotates until grounding of the Terminal No. 5 C-33 is removed, thus stopping the motor.