Page 640 of 3066
ATC-62
TROUBLE DIAGNOSIS
INSPECTION FLOW
SYSTEM DESCRIPTION
Component Parts
Air mix door control system components are:
lAuto amp.
lAir mix door motor (LCU)
lA/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
*1 Self-diagnosisAT C - 4 2, see No.1 *6 Self-diagnosisAT C -4 2, see No. 14. *11 Intake sensor circuitATC-101
*2 Ambient sensor circuitAT C - 9 3*7 LAN system circuitAT C - 5 6*12 Self-diagnosisAT C - 4 2,seeNo.7
*3 In-vehicle sensor circuitAT C - 9 5
*8 Operational checkAT C - 5 1
*4 Sunload sensor circuitAT C - 9 8*9 Operational checkAT C - 5 1
*5 Air mix door motor circuitAT C - 6 1*10 Symptom tableAT C - 3 0
RJIA0515E
Page 641 of 3066
TROUBLE DIAGNOSIS
ATC-63
C
D
E
F
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MA
B
AT C
lIn-vehicle sensor
lAmbient sensor
lSunload sensor
lIntake sensor
System Operation
The auto amplifier receives data from each of the sensors. The amplifier sends air mix door, mode door and
intake door motor 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 auto amplifier and each of the motor posi-
tion sensors are compared by the LCUs in each motor with the existing decision and opening angles. Subse-
quently, HOT/COLD or DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The new
selection data is returned to the auto amplifier.
Air Mix Door Control Specification
RHA424GB
RHA457H
Page 643 of 3066
TROUBLE DIAGNOSIS
ATC-65
C
D
E
F
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AT C
INSPECTION FLOW
SYSTEM DESCRIPTION
Component Parts
Intake door control system components are:
lAuto amp.
lIntake door motor (LCU)
*1 Self-diagnosisAT C - 4 2, see No.1 *6 Self-diagnosisAT C - 4 2, see No. 14. *11 Operational checkAT C - 5 1
*2 Ambient sensorAT C - 9 3*7 LAN system circuitAT C -5 6*12 Symptom tableAT C - 3 0
*3 In-vehicle sensorAT C - 9 5*8 Component description for intake
door motorAT C - 6 6*13 Intake sensor circuitATC-101, "Intake
Sensor Circuit"
*4 Sunload sensorAT C - 9 8*9 Operational checkAT C - 5 1
*5 Air mix door motor circuitAT C - 6 1*10 Self-diagnosisAT C - 4 2, see No.5 or 7
RJIA0518E
Page 644 of 3066

ATC-66
TROUBLE DIAGNOSIS
lA/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
lIn-vehicle sensor
lAmbient sensor
lSunload sensor
lIntake sensor
System Operation
The auto amplifier receives data from each of the sensors. The amplifier sends air mix door, mode door and
intake door motor 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 auto amplifier and each of the motor posi-
tion sensors are compared by the LCUs in each motor with the existing decision and opening angles. Subse-
quently, HOT/COLD or DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The new
selection data is returned to the auto amplifier.
COMPONENT DESCRIPTION
Intake door motor
The intake door motor is attached to the intake unit. It rotates so that
air is drawn from inlets set by the auto amplifier. Motor rotation is
conveyed to a lever which activates the intake door.
SHA431F
RJIA0519E
Page 646 of 3066
ATC-68
TROUBLE DIAGNOSIS
INSPECTION FLOW
*1 Self-diagnosisAT C -4 2*2 Ambient sensor circuitAT C - 9 3*3 In-vehicle sensor circuitAT C - 9 5
*4 Sunload sensor circuitAT C - 9 8*5 Air mix door motor circuitAT C - 6 1*6 Self-diagnosisAT C - 4 2,see No.13.
*7 Blower motor circuitAT C -6 7
*8 Self-diagnosisAT C -4 2*9 Operational checkAT C -5 1
*10 Symptom tableAT C -3 0*11 Operational checkAT C - 5 1*12 Intake sensor circuitATC-101
*13 With gasoline engine: Water tempera-
ture sensor ,DI-13
(LHD),DI-31
(RHD)
With diesel engine: Thermal transmit-
ter,DI-13
(LHD),DI-31(RHD)
RJIA0521E
Page 647 of 3066

TROUBLE DIAGNOSIS
ATC-69
C
D
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AT C
SYSTEM DESCRIPTION
Component Parts
Fan speed control system components are:
lAuto amp.
lA/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
lFan control amp.
lIn-vehicle sensor
lAmbient sensor
lSunload sensor
lIntake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the automatic amplifier based on input from
the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor.
The blower motor applied voltage ranges from approximately 4 volts (lowest speed) to 12 volts (highest
speed).
The control blower speed (in the range of 4 to 12V), the automatic amplifier supplies a gate voltage to the fan
control amplifier. Based on this voltage, the fan control amplifier controls the voltage supplied to the blower
motor.
Starting Fan Speed Control
Start Up From COLD SOAK Condition (Automatic mode)
In a cold start up condition where the engine coolant temperature is below 56°C (133°F), the blower will not
operate for a short period of time (up to 150 seconds). The exact start delay time varies depending on the
ambient and engine coolant temperature.
In the most extreme case (very low ambient) the blower starting delay will be 150 seconds as described
above. After this delay, the blower will operate at low speed until the engine coolant temperature rises above
56°C (133°F), at which time the blower speed will increase to the objective speed.
Start Up From Normal or HOT SOAK Condition (Automatic mode)
The blower will begin operation momentarily after the A/C button is pushed. The blower speed will gradually
rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
Blower Speed Compensation
Sunload
SHA006FD
Page 652 of 3066
ATC-74
TROUBLE DIAGNOSIS
INSPECTION FLOW
SYSTEM DESCRIPTION
Auto amplifier controls compressor operation by ambient temperature and signal from ECM.
*1 Self-diagnosisAT C - 4 2, see No.1. *6 Self-diagnosisAT C -4 2, see No. 14. *11 Operational checkAT C -5 1
*2 Ambient sensor circuitAT C - 9 3*7 Magnet clutch circuitAT C -7 3*12 Symptom tableAT C - 3 0
*3 In-vehicle sensor circuitAT C - 9 5*8 Trouble diagnoses for abnormal pres-
sureAT C -8 6*13 Intake sensor circuitATC-101
*4 Sunload sensor circuitAT C - 9 8*9 Operational checkAT C - 5 1
*5 Air mix door motor circuitAT C - 6 1*10 Self-diagnosisAT C -4 2,seeNo.7.
RJIA0533E
Page 653 of 3066
TROUBLE DIAGNOSIS
ATC-75
C
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AT C
Low Temperature Protection Control (With Gasoline Engine)
Auto amplifier will turn the compressor ON or OFF as determined by
a signal detected by ambient sensor.
When ambient temperatures are greater than -2°C(28°F), the com-
pressor turns ON. The compressor turns OFF when ambient temper-
atures are less than -5°C(23°F).
Evaporator Freeze Protection Control (With Diesel Engine)
Auto amplifier will turn the compressor ON or OFF as determined by
a signal detected by intake sensor.
When intake temperatures are greater than 4°C(39°F), the com-
pressor turns ON. The compressor turns OFF when intake tempera-
tures are less than 2.5°C (36.5°F).
DIAGNOSTIC PROCEDURE
SYMPTOM: Magnet clutch does not engage when A/C switch is ON.
RHA094GB
RJIA0534E
RJIA0535E