System Construction

AIR CONDITIONER CONTROL


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 signals from its various dials and switches. The front air control 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 below.
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
- Interference from other signal 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
The air mix door is controlled by the front air control based on input from the temperature dial setting.

Blower Speed Control
Blower speed is controlled by the front air control based on the position of the blower control dial.
With the blower control dial set to any position except OFF, the blower will begin to operate.

Intake Door Control
The intake door is controlled by the front air control based on input from the recirculation switch setting, and the MAX A/C switch setting.

Mode Door Control
The mode door is controlled by the front air control based on input from the mode dial setting.

Magnet Clutch Control





The ECM controls compressor operation using input signals from the throttle position sensor and front air control.