INFINITI FX35 2005 Service Manual

ATC-74
TROUBLE DIAGNOSIS
Revision: 2005 July 2005 FX
SYSTEM DESCRIPTION
Component Parts
Air mix door control system components are:

Unified meter and A/C amp.

Air mix door motor (LCU)

A/C LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)

In-vehicle sensor

Ambient sensor

Sunload sensor

Intake sensor
System Operation
The unified meter and A/C amp. receives data from each of the sensors. The unified meter and A/C amp.
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 unified meter and A/C amp. and each of
the motor position sensors are compared by the LCUs in each door motor with the existing decision and open-
ing angles. Subsequently, HOT/COLD, DEF/VENT and FRESH/RECIRCULATION operation is selected. The
new selection data are returned to the unified meter and A/C amp.
Air Mix Door Control Specification
RJIA1781E
RJIA1782E

TROUBLE DIAGNOSIS ATC-75
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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 unified meter and A/C amp. Motor rotation is then sent con-
veyed through a shaft and the air mix door position feedback is then
sent to the unified meter and A/C amp. by PBR built-in air mix door
motor.
DIAGNOSIS PROCEDURE FOR AIR MIX DOOR MOTOR
SYMPTOM: Discharge air temperature does not change.
Perform diagnosis procedure. Refer to AT C - 6 6 , "
DIAGNOSIS PROCEDURE FOR LAN CIRCUIT" .
Air Mix Door Motor PBR CircuitAJS0014V
SYMPTOM:

Discharge air temperature does not change.

PBR circuit is open or shorted.
DIAGNOSIS PROCEDURE FOR AIR MIX DOOR MOTOR PBR
Perform diagnosis procedure. Refer to AT C - 6 6 , "DIAGNOSIS PROCEDURE FOR LAN CIRCUIT" .
RJIA0893E
RJIA0894E

ATC-76
TROUBLE DIAGNOSIS
Revision: 2005 July 2005 FX
Intake Door Motor CircuitAJS0014W
SYMPTOM:

Intake door does not change.

Intake door motor does not operate normally.
INSPECTION FLOW
*1AT C - 5 4 , "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 4 to 6. *2
ATC-104, "
Ambient Sensor Circuit"*3 ATC-107, "In-vehicle Sensor Circuit"
*4 AT C - 11 0 , "Sunload Sensor Circuit"*5AT C - 7 3 , "Air Mix Door Motor Circuit"*6 AT C - 5 4 , "FUNCTION CONFIRMA-
TION PROCEDURE", see No. 13.
*7 AT C - 6 6 , "
LAN System Circuit"*8ATC-124, "INTAKE DOOR MOTOR"*9 AT C - 6 1 , "Operational Check"
*10 AT C - 4 2 , "SYMPTOM TABLE"*11AT C - 11 3 , "Intake Sensor Circuit"
RJIA1993E

TROUBLE DIAGNOSIS ATC-77
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Revision: 2005 July 2005 FX
SYSTEM DESCRIPTION
Component Parts
Intake door control system components are:

Unified meter and A/C amp.

Intake door motor (LCU)

A/C LAN system (PBR built-in mode door motor, air mix 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 the DEF, or OFF switches are pressed or A/C switch is OFF,
the unified meter and A/C amp. sets the intake door at the FRESH position.
Intake Door Control Specification
RJIA1786E
RJIA1787E

ATC-78
TROUBLE DIAGNOSIS
Revision: 2005 July 2005 FX
COMPONENT DESCRIPTION
Intake Door Motor
The intake door motor is attached to the blower unit. It rotates so that
air is drawn from inlets set by the unified meter and A/C amp. Motor
rotation is conveyed to a lever which activates the intake door.
DIAGNOSIS PROCEDURE FOR INTAKE DOOR MOTOR
SYMPTOM: Intake door motor does not operate normally.
Perform diagnosis procedure. Refer to AT C - 6 6 , "
DIAGNOSIS PROCEDURE FOR LAN CIRCUIT" .
RJIA0897E

TROUBLE DIAGNOSIS ATC-79
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Revision: 2005 July 2005 FX
Blower Motor CircuitAJS0014X
SYMPTOM: Blower motor operation is malfunctioning.
INSPECTION FLOW
*1ATC-61, "Operational Check"*2AT C - 11 3 , "Intake Sensor Circuit"*3ATC-54, "FUNCTION CONFIRMA-
TION PROCEDURE", see No.4.
*4 ATC-54, "
FUNCTION CONFIRMA-
TION PROCEDURE", see No.6. *5
AT C - 5 4 , "
FUNCTION CONFIRMA-
TION PROCEDURE", see No.13. *6
ATC-81, "
DIAGNOSIS PROCE-
DURE FOR BLOWER MOTOR"
*7 ATC-42, "SYMPTOM TABLE"*8ATC-104, "Ambient Sensor Circuit"*9ATC-107, "In-vehicle Sensor Circuit"
*10 ATC-110, "Sunload Sensor Circuit"*11EC-208, "DTC P0117, P0118 ECT
SENSOR" (VQ35DE) or EC-914,
"DTC P0117, P0118 ECT SEN-
SOR" (VK45DE)
RJIA1994E

ATC-80
TROUBLE DIAGNOSIS
Revision: 2005 July 2005 FX
SYSTEM DESCRIPTION
Component Parts
Fan speed control system components are:

Unified meter and A/C amp.

A/C LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)

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 unified meter and A/C amp. based on the
input from the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor.
When the air flow is increased, the duty ratio of the blower fan motor’s drive signal is changed at 8%/sec. to
prevent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
RJIA1995E

TROUBLE DIAGNOSIS ATC-81
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Revision: 2005 July 2005 FX
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 AUTO 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
speed is at duty ratio 25%. During high sunload conditions, the unified meter and A/C amp. raise the blower
speed (duty ratio 49%).
Fan Speed Control Specification
COMPONENT DESCRIPTION
Brush-Less Motor
The blower motor utilizes a brush-less motor with a rotating magnet.
Quietness is improved over previous motors where the brush was
the point of contact and the coil rotated.
DIAGNOSIS PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning.
RJIA1996E
ZHA152H
SJIA0266E

ATC-82
TROUBLE DIAGNOSIS
Revision: 2005 July 2005 FX
1. CHECK POWER SUPPLY FOR BLOWER MOTOR
1. Disconnect blower motor connector.
2. Turn ignition switch ON.
3. Check voltage between blower motor harness connector M78 terminal 1 (L/W) and ground.
OK or NG
OK >> GO TO 2.
NG >> Check power supply circuit and 15 A fuses [Nos. 10 and 11, located in the fuse block (J/B)]. Refer to PG-82,
"FUSE BLOCK - JUNCTION BOX (J/B)" .

If fuses are OK, check harness for open circuit. Repair or replace if necessary.

If fuses are NG, replace fuse and check harness for short circuit. Repair or replace if necessary.
2. CHECK BLOWER MOTOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between blower motor harness connector M78 terminal 3 (B) and ground.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK CIRCUIT CONTINUITY BETWEEN BLOWER MOTOR AND UNIFIED METER AND A/C AMP.
1. Disconnect unified meter and A/C amp. connector.
2. Check continuity between blower motor harness connector M78 terminal 2 (G) and unified meter and A/C amp. harness connec-
tor M57 terminal 53 (G).
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector. 1 – Ground : Battery voltage
RJIA1997E
3 – Ground : Continuity should exist.
RJIA1998E
2 – 53 : Continuity should exist.
RJIA1999E

TROUBLE DIAGNOSIS ATC-83
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4. CHECK UNIFIED METER AND A/C AMP. OUTPUT SIGNAL
1. Reconnect blower motor connector and unified meter and A/C amp. connector.
2. Turn ignition switch ON.
3. Change the fan speed from Lo to Hi, and check the duty ratios between blower motor harness connector M78 terminal 2 (G) and ground using an oscilloscope. Normal terminal 2 (G) drive signal duty ratios are
shown in the table below.
OK or NG
OK >> Replace blower motor after confirming the fan air flow does not change.
NG >> Replace unified meter and A/C amp.
COMPONENT INSPECTION
Blower Motor
Confirm smooth rotation of the blower motor.

Ensure that there are no foreign particles inside the blower unit.
RJIA2000E
RJIA2001E
RJIA0905E