Air Conditioner Control System
AIR CONDITIONER CONTROLDescription
The front air control provides automatic regulation of the vehicle's interior temperature. The system is based on the driver's and passenger's selected "set temperature", regardless of the outside temperature changes. This is done by utilizing a microcomputer, also referred to as the front air control, which receives input signals from the following six sensors:
- Ambient sensor
- In-vehicle sensor
- Intake sensor
- Optical sensor (one sensor for driver and passenger side)
- PBR (Position Balanced Resistor).
- Vehicle speed sensor
The front air control uses these signals (including the set temperature) to automatically control:
- Outlet air volume
- Air temperature
- Air distribution
The front air control also provides separate regulation of the vehicle's interior temperature for the rear passenger area. The system is based on the temperature and rear blower settings selected from rear control switches located on the front air control, or from the temperature and rear blower settings selected from rear control switches on the rear air control, when the front air control switches are set to the rear position.
The front air control is used to select:
- Outlet air volume
- Air temperature/distribution
Operation
AIR MIX DOORS CONTROL
The air mix doors are automatically controlled so that in-vehicle temperature is maintained at a predetermined value by the temperature setting, ambient temperature, in-vehicle temperature and amount of sunload.
BLOWER SPEED CONTROL
Blower speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, intake temperature, amount of sunload and air mix door position. When AUTO switch is pressed, the blower motor starts to gradually increase air flow volume (if required). When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flowing.
INTAKE DOOR CONTROL
The intake door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, intake temperature, amount of sunload and by the ON-OFF operation of the compressor.
MODE DOOR CONTROL
The mode door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, intake temperature and amount of sunload.
DEFROSTER DOOR CONTROL
The defroster door is controlled by: Turning the defroster dial to front defroster.
MAGNET CLUTCH CONTROL
When A/C switch or DEF switch is pressed, front air control inputs compressor ON signal to BCM. BCM sends compressor ON signal to ECM, via CAN communication line.
ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant pressure sensor signal, throttle angle sensor, etc.). If it judges compressor can be turned ON, it sends compressor ON signal to IPDM E/R, via CAN communication line.
Upon receipt of compressor ON signal from ECM, IPDM E/R turns air conditioner relay ON to operate compressor.
SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the front air control to quickly locate the cause of symptoms. Refer to "A/C System Self-diagnosis Function"
Description of Control System
The control system consists of input sensors, switches, the front air control (microcomputer) and outputs. The relationship of these components is shown in the figure.