Air Conditioner Control
AIR CONDITIONER CONTROLOverview Air Conditioner LAN Control System
The LAN (local area network) system consists of front air control, air mix door motor, intake door motor, and mode door motor.
A configuration of these components is shown in the diagram.
System Construction
A small network is constructed between the front air control, air mix door motor, intake door motor, and mode door motor. The front air control and motors are connected by data transmission lines and motor power supply lines. The LAN network is built through the ground circuits of the two motors.
Addresses, motor opening angle signals, motor stop signals and error checking messages are all transmitted through the data transmission lines connecting the front air control and each motor.
The following functions are contained in LCUs built into the air mix door motor, intake door motor, and the mode door motor.
- Address
- Motor opening angle signals
- Data transmission
- Motor stop and drive decision
- Opening angle sensor (PBR function)
- Comparison
- Decision (front air control indicated value and motor opening angle comparison)
OPERATION
The front air control receives data from each of the sensors. It then sends air mix door, mode door and intake door opening angle data to the air mix door motor LCU, mode door motor LCU and intake door motor LCU. The air mix door motor, mode door motor and intake door motor read their respective signals according to the address signal. Opening angle indication signals received from the front air control and each of the motor position sensors are compared by the LCUs in each motor with the existing decision and opening angles. Subsequently, HOT/COLD, DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The new selection data is returned to the front air control.
TRANSMISSION DATA AND TRANSMISSION ORDER
Front air control data is transmitted consecutively to each of the door motors following the form shown in figure.
Start: Initial compulsory signal sent to each of the door motors.
Address: Data sent from the front air control is selected according to data-based decisions made by the air mix door motor, mode door motor and intake door motor.
If the addresses are identical, the opening angle data and error check signals are received by the door motor LCUs. The LCUs then make the appropriate error decision. If the opening angle data is normal, door control begins.
If an error exists, the received data is rejected and corrected data received. Finally, door control is based upon the corrected opening angle data.
Opening angle: Data that shows the indicated door opening angle of each door motor.
Error check: Procedure by which sent and received data is checked for errors. Error data is then compiled. The error check prevents corrupted data from being used by the air mix door motor, mode door motor and intake door motor. Error data can be related to the following problems.
- Abnormal electrical frequency
- Poor electrical connections
- Signal leakage from transmission lines
- Signal level fluctuation
Stop signal: At the end of each transmission, a stop operation, in-operation, or internal problem message is delivered to the front air control. This completes one data transmission and control cycle.
AIR MIX DOOR CONTROL (AUTOMATIC TEMPERATURE CONTROL)
The air mix door is 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.
FAN SPEED CONTROL
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle temperature, intake temperature, amount of sunload and air mix door position.
With fan switch set to AUTO, the blower motor starts to gradually increase air flow volume.
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 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.
MAGNET CLUTCH CONTROL
The ECM controls compressor operation using input signals from the throttle position sensor and front air control.
Overview of Control system
The control system consists of input sensors, switches, the front air control and outputs.