Page 3473 of 4179

TROUBLE DIAGNOSIS
ATC-77
C
D
E
F
G
H
I
K
L
MA
B
AT C
SYSTEM DESCRIPTION
Component Parts
Air mix door control system components are:
Auto amp.
Air mix door motor (LCU)
A/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
In-vehicle sensor
Ambient sensor
Sunload sensor
Intake sensor
System Operation
The auto amp. receives data from each of the sensors. The auto amp 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 auto amp. and each of the motor position
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 selec-
tion data is returned to the auto amp.
Air Mix Door Control Specification
RHA424GB
RHA457H
Page 3474 of 4179
ATC-78
TROUBLE DIAGNOSIS
COMPONENT DESCRIPTION
Air Mix Door Motor
The air mix door motor is attached to the heater & cooling unit. It
rotates so that the air mix door is opened or closed to a position set
by the auto amp. The air mix door position is fed back to the auto
amp. by PBR built-in air mix door motor.
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
SYMPTOM: Discharge air temperature does not change.
Perform diagnostic procedure. Refer to AT C - 6 9 , "
DIAGNOSTIC PROCEDURE FOR LAN CIRCUIT" .
RJIA0516E
RJIA0517E
Page 3475 of 4179
TROUBLE DIAGNOSIS
ATC-79
C
D
E
F
G
H
I
K
L
MA
B
AT C
Intake Door Motor CircuitEJS004YM
SYMPTOM:
Intake door does not change.
Intake door motor does not operate normally.
INSPECTION FLOW
*1ATC-65, "Operational Check".*2ATC-59, "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 1.*3AT C - 5 9 , "
FUNCTION CONFIRMA-
TION PROCEDURE", see No.5 to
7.
*4ATC-109, "
Ambient Sensor Circuit".*5AT C - 111 , "In-vehicle Sensor Circuit".*6AT C - 11 4 , "Sunload Sensor Circuit".
*7ATC-117, "
Intake Sensor Circuit".*8ATC-76, "Air Mix Door Motor Circuit".*9AT C - 3 4 , "SYMPTOM TABLE".
*10ATC-59, "
FUNCTION CONFIRMA-
TION PROCEDURE", see No. 9.*11ATC-69, "
LAN System Circuit".*12ATC-128, "INTAKE DOOR
MOTOR".
RJIA3099E
Page 3476 of 4179
ATC-80
TROUBLE DIAGNOSIS
SYSTEM DESCRIPTION
Component Parts
Intake door control system components are:
Auto amp.
Intake door motor (LCU)
A/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
In-vehicle sensor
Ambient sensor
Sunload sensor
Intake sensor
System Operation
The intake door control determines intake door position based on the ambient temperature, the intake air tem-
perature and the in-vehicle temperature. When set mode control dial to D/F, D/F2 or DEF position, or OFF
switch is pushed, the auto amp. sets the intake door at the FRESH position.
Intake Door Control Specification
RJIA2831E
RHA383H
Page 3477 of 4179
TROUBLE DIAGNOSIS
ATC-81
C
D
E
F
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H
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K
L
MA
B
AT C
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 amp. Motor rotation is con-
veyed to a lever which activates the intake door.
DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR
SYMPTOM: Intake door motor does not operate normally.
Perform diagnostic procedure. Refer to AT C - 6 9 , "
DIAGNOSTIC PROCEDURE FOR LAN CIRCUIT" .
RJIA0519E
RJIA0520E
Page 3478 of 4179
ATC-82
TROUBLE DIAGNOSIS
Blower Motor CircuitEJS004YN
SYMPTOM:
Blower motor operation is malfunctioning.
Blower motor operation is malfunctioning under out of starting fan speed control.
INSPECTION FLOW
*1ATC-65, "Operational Check".*2ATC-59, "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 1.*3ATC-59, "
FUNCTION CONFIRMA-
TION PROCEDURE", see No. 5.
*4ATC-59, "
FUNCTION CONFIRMA-
TION PROCEDURE", see No. 7.*5ATC-109, "
Ambient Sensor Circuit".*6AT C - 111 , "In-vehicle Sensor Circuit".
RJIA3101E
Page 3479 of 4179

TROUBLE DIAGNOSIS
ATC-83
C
D
E
F
G
H
I
K
L
MA
B
AT C
SYSTEM DESCRIPTION
Component Parts
Fan speed control system components are:
Auto amp.
A/C LAN system (PBR built-in air mix door motor, mode door motor and intake door motor)
Fan control amp.
In-vehicle sensor
Ambient sensor
Sunload sensor
Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the auto amp. 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 auto amp. supplies a gate voltage to the fan control
amp. Based on this voltage, the fan control amp. controls the voltage supplied to the blower motor.
*7AT C - 11 4 , "Sunload Sensor Circuit".*8ATC-117, "Intake Sensor Circuit".*9AT C - 3 4 , "SYMPTOM TABLE".
*10AT C - 5 9 , "
FUNCTION CONFIRMA-
TION PROCEDURE", see No. 9.*11ATC-84, "
DIAGNOSTIC PROCE-
DURE FOR BLOWER MOTOR".*12 QR engine; (WITH EURO-OBD) EC-162, "DTC P0117, P0118 ECT SEN-
SOR" .
QR engine; (WITHOUT EURO-OBD)
EC-597, "
DTC P0117, P0118 ECT
SENSOR" .
YD engine; (WITH EURO-OBD) EC-
981, "DTC P0117, P0118 ECT SEN-
SOR" .
YD engine; (WITHOUT EURO-OBD)
EC-1291, "
DTC P0117, P0118 ECT
SENSOR" .
RJIA2833E
Page 3480 of 4179

ATC-84
TROUBLE DIAGNOSIS
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), and then the blower speed will increase to the objective speed.
Start Up from Usual or HOT SOAK Condition (Automatic mode)
The blower will begin operation momentarily after the A/C switch 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
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The low speed will vary depending on the sunload. During conditions of low or no sunload, the blower
low speed is usual low speed (approx. 4V). During high sunload conditions, the auto amp. causes the blower
fan speed to increase.(Approx. 7V)
Fan Speed Control Specification
COMPONENT DESCRIPTION
Fan Control Amp.
The fan control amp. is located on the intake unit. The fan control
amp. receives a gate voltage from the auto amp. to steplessly main-
tain the blower fan motor voltage in the 4 to 12 volt range.
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning.
RJIA0522E
RJIA0523E
RHA467GA