Air Conditioner LAN System

LAN Control System:

Overview Air Conditioner LAN Control System
The LAN (Local Area Network) system consists of display and A/C auto amp. mode door motor air mix door motor and intake door motor.

A configuration of these components is shown in the diagram.







SYSTEM CONSTRUCTION (LAN)
A small network is constructed between the display and A/C auto amp. air mix door motor mode door motor and intake door motor. The display and A/C auto amp. and motors are connected by data transmission lines and motor power supply lines. The LAN network is built through the ground circuits of the three motors.

Addresses motor opening angle signals motor stop signals and error checking messages are all transmitted through the data transmission lines connecting the display and A/C auto amp. and three motors.

The following functions are contained in LCUs built into the air mix door motor mode door motor and intake door motor.
- Address
- Motor opening angle signals
- Data transmission
- Motor stop and drive decision
- Opening angle sensor (PBR function)
- Comparison
- Decision (Display and A/C auto amp. indicated value and motor opening angle comparison)

LAN Operation:

OPERATION
The display and A/C auto amp. receives data from each of the sensors. The display and A/C auto amp. sends mode door air mix door and intake door opening angle data to the mode door motor LCU air mix door motor LCU and intake door motor LCU.

The mode door motor air mix door motor and intake door motor read their respective signals according to the address signal. Opening angle indication signals received from the display and A/C auto amp. 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 display and A/C auto amp.

TRANSMISSION DATA AND TRANSMISSION ORDER
Display and A/C auto amp. 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 auto amplifier 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 usual 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 symptoms.
- Unusual 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 error message is delivered to the auto amplifier. 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 sun load 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 doors are automatically controlled by: The temperature setting ambient temperature in-vehicle temperature intake temperature amount of sunload and ON-OFF operation of the compressor.

OUTLET DOOR CONTROL
The outlet door is automatically controlled by: The temperature setting ambient temperature in-vehicle temperature intake temperature and amount of sunload.







MAGNET CLUTCH CONTROL
When A/C switch AUTO.ECON switch or DEF switch is pressed display and A/C auto amp. 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 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.

When sending compressor ON signal to IPDM E/R via CAN communication line ECM simultaneously sends compressor feedback signal to meter control unit via CAN communication line.

Meter control unit sends compressor feedback signal to display and A/C auto amp. Display and A/C auto amp then uses input compressor feedback signal to control air inlet.

SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the display and A/C auto amp. to quickly locate the cause of symptoms.