Page 2003 of 3189

AIR CONDITIONER CONTROL
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TRANSMISSION DATA AND TRANSMISSION ORDER
Amplifier 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 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 problems.
●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 problem 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.
RHA351H
RHA352H
Page 2004 of 3189

ATC-24
AIR CONDITIONER CONTROL
FAN SPEED CONTROL
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle tem-
perature, 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 flow-
ing.
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 tem-
perature, intake temperature and amount of sunload.
MAGNET CLUTCH CONTROL
The ECM controls compressor operation using input signals from the refrigerant pressure sensor (with QG
engine), throttle position sensor and auto amplifier.
SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the auto amplifier (LCU) to quickly locate the cause of problems.
Overview of Control systemEJS001Z7
The control system consists of input sensors, switches, the automatic amplifier (microcomputer) and outputs.
The relationship of these components is shown in the diagram below:
RJIA0687E
Page 2005 of 3189

AIR CONDITIONER CONTROL
ATC-25
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Control OperationEJS001Z8
DISPLAY SCREEN
Displays the operational status of the system.
AUTO SWITCH
The compressor, intake doors, air mix doors, outlet doors and blower speed are automatically controlled so
that the in-vehicle temperature will reach, and be maintained at the set temperature selected by the operator.
TEMPERATURE DIAL (POTENTIO TEMPERATURE CONTROL)
Increase or decrease the set temperature.
A/C SWITCH
The compressor is ON or OFF.
(Pressing the A/C switch when the AUTO switch is ON will turn off the A/C switch and compressor.)
DEFROSTER (DEF) SWITCH
Positions the air outlet doors to the defrost position. Also positions the intake doors to the outside air position.
MODE SWITCH
Control the air discharge outlets.
FAN SWITCH
Manually controls the blower speed. Five speeds are available for manual control (as shown on the display
screen).
OFF SWITCH
The compressor and blower are OFF, the intake doors are set to the outside air position, and the air outlet
doors are set to the foot position.
FRESH (FRE) SWITCH
OFF position: Interior air is recirculated inside the vehicle.
ON position: Outside air is drawn into the passenger compartment.
(When RECIRCULATION switch is ON, the FRESH switch turns OFF automatically.)
RJIA1675E
Page 2006 of 3189
ATC-26
AIR CONDITIONER CONTROL
RECIRCULATION (REC) SWITCH
OFF position: Outside air is drawn into the passenger compartment.
ON position: Interior air is drawn into the passenger compartment.
(When the FRESH switch is ON or the compressor is turned from ON to OFF, the RECIRCULATION switch
turns OFF automatically.)
REAR WINDOW DEFOGGER SWITCH
When illumination is ON, rear window is defogged.
Fail-safe FunctionEJS001Z9
If fail-safe request signal is sent from AV control unit, or if communication error exists between auto amplifier
and AV control unit for at least 30 seconds, air conditioner is controlled under following conditions.
Compressor : ON
Air inlet : Fresh
Air outlet : AUTO
Blower fan speed : AUTO
Set temperature : Setting before communication error occurs
Page 2007 of 3189
AIR CONDITIONER CONTROL
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Discharge Air FlowEJS001ZA
RJIA1676E
Page 2008 of 3189
ATC-28
AIR CONDITIONER CONTROL
System Description
EJS001ZB
SWITCHES AND THEIR CONTROL FUNCTION
RHA592H
RJIA1677E
Page 2023 of 3189

TROUBLE DIAGNOSIS
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FUNCTION CONFIRMATION PROCEDURE
1.SET IN SELF-DIAGNOSTIC MODE
Method 1 (Without navigation system, or with navigation system)
1. Turn ignition switch to ON.
2. Within 10 seconds after starting engine (ignition switch is turned ON.), press and hold OFF switch for at
least 5 seconds.
3. The self-diagnosis (step 1) should start.
Method 2 (Only with navigation system)
1. Turn OFF the audio system.
2. While pressing “Vehicle Information” switch, turn audio switch (volume adjustment dial) by at least 30
notches.
3. Trouble diagnosis initial screen appears. Using joystick, select “Confirmation and Adjustment”. And press
“Confirm”.
4. Confirmation and adjustment initial screen appears. Using joystick, select “Air-conditioner trouble diagno-
sis”, and press “Confirm” to start self-diagnosis (step 1).
CAUTION:
If battery voltage drops below 12V during step diagnosis 3, actuator speed becomes slower and as a
result, the system may generate an error even when operation is normal. To avoid this, start engine
before performing this diagnosis.
>> GO TO 2.
Page 2035 of 3189

TROUBLE DIAGNOSIS
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Power Supply and Ground Circuit for Auto Amp.EJS001ZJ
SYMPTOM: A/C system does not come on.
INSPECTION FLOW
COMPONENT DESCRIPTION
Automatic Amplifier (Auto Amp.)
The auto amplifier has a built-in microcomputer which processes
information sent from various sensors needed for air conditioner
operation. The air mix door motor, mode door motor, intake door
motor, blower motor and compressor are then controlled.
The auto amplifier is unitized with control mechanisms. When the
various switches and temperature adjustment dial are operated, data
is input to the auto amp. from the AV AND NAVI CONTROL UNIT (or
DISPLAY) using multiplex communication.
Self-diagnostic functions are also built into auto amplifier to provide
quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
The PTC is built into the multi-function switch. It can be set at an
interval of 0.5°C (1.0°F) in the 18°C (60°F) to 32°C (90°F) tempera-
ture range by turning the temperature dial. The set temperature is
displayed.
*1 EL-11, "POWER SUPPLY ROUT-
ING"*2AT C - 5 1 , "Operational Check"*3AT C - 5 6 , "DIAGNOSTIC PROCE-
DURE FOR A/C SYSTEM"
RJIA1691E
RJIA0750E
RJIA1692E