2005 INFINITI QX4 air condition

TROUBLE DIAGNOSIS
ATC-85
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
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 front air control. Motor rotation is
conveyed to a lever which activates the intake door.
DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR
1. CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Check voltage between front air control harness connector M49
terminal 7 and terminal 8 while placing the HVAC system into
self-diagnostic mode.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK INTAKE DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 7, 8 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
WJIA0552E
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M497 8Self-diagnostic
modeBattery
voltage
WJIA1757E
7 - Ground : Continuity should not exist.
8 - Ground : Continuity should not exist.
WJIA1758E

ATC-86
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
3. CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the BACK button to back out of self-diagnostic mode.
2. Check voltage between front air control harness connector M49
terminal 7 and terminal 8 while placing the HVAC system into
self-diagnostic mode.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-147, "
FRONT AIR CONTROL" .
4. CHECK INTAKE DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 7 and terminal 8.
OK or NG
OK >> Replace intake door motor. Refer to ATC-164, "Removal
and Installation" .
NG >> GO TO 5.
5. CHECK INTAKE DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the intake door motor harness connector.
2. Check continuity between front air control harness connector
M49 terminal 7, 8 and the intake door motor harness connector
M58 terminal 1, 6.
OK or NG
OK >> Replace intake door motor. Refer to ATC-164, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M498 7Self-diagnostic
modeBattery
voltage
WJIA1759E
Continuity should exist.
WJIA1760E
1 - 7 : Continuity should exist.
6 - 8 : Continuity should exist.
WJIA0591E

TROUBLE DIAGNOSIS
ATC-89
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
DIAGNOSTIC PROCEDURE FOR DEFROSTER DOOR MOTOR
1. CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the defroster switch ( ).
3. Check voltage between front air control harness connector M49
terminal 20 and terminal 19 and press the defroster switch ( )
again.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 19, 20 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
3. CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the defroster switch ( ).
2. Check voltage between front air control harness connector M49
terminal 19 and terminal 20 and press the defroster switch ( )
again.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-147, "
FRONT AIR CONTROL" .
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M4920 19Press
defroster
switchBattery
voltage
WJIA1765E
19 - Ground : Continuity should not exist.
20 - Ground : Continuity should not exist.
WJIA1766E
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M4919 20Press
defroster
switchBattery
voltage
WJIA1767E

ATC-94
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:

Front air control

Front blower motor

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control
based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the blower motor speed is adjusted gradually 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.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50°C (122°F), the blower will not
operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies
depending on the ambient and engine coolant temperatures.
In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as
described above. After the coolant temperature reaches 50°C (122°F), or the 210 seconds has elapsed, the
blower speed will increase to the objective blower speed.
Start up from usual operating 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).
WJIA1357E

TROUBLE DIAGNOSIS
ATC-95
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
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 speed will vary depending on the sunload. During conditions of low or no sunload, the blower
operates at low speed. During high sunload conditions, the front air control causes the blower speed to
increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the cooling unit. The vari-
able blower control receives a gate voltage from the front air control
to steplessly maintain the blower motor voltage in the 0 to 5 volt
range (approx.).
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning under starting
blower speed control.
WJIA0441E
WJIA0559E
WJIA1358E

ATC-118
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal
27 (W/R) and front air control harness connector M49 terminal
12 (W/R).
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VOLTAGE FOR FRONT AIR CONTROL (COMPRESSOR ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 12 (W/R) and ground.
OK or NG
OK >> GO TO 8.
NG-1 >> If the voltage is approx. 5V when A/C switch is ON, replace front air control. Refer to ATC-147,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-20, "
Removal
and Installation of BCM" . 27 - 12 Continuity should exist.
WJIA1443E
Terminals
Condition Voltage (+)
(-) Front air
control con-
nectorTe r m i n a l N o .
(Wire color)
M49 12 (W/R) GroundA/C switch: ON Approx. 0V
A/C switch: OFF Approx. 5V
WJIA0449E

TROUBLE DIAGNOSIS
ATC-119
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to ATC-33, "
CONSULT-II Function (HVAC)" .
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal
70 (B/W) and ground.
OK or NG
OK >>
WITH CONSULT-II
GO TO 9.

WITHOUT CONSULT-II
GO TO 10.
NG >> Refer to EC-643, "
REFRIGERANT PRESSURE SENSOR" .
9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to ATC-33, "
CONSULT-II Function
(HVAC)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal
28 (L/R) and front air control harness connector M49 terminal 10
(L/R).
OK or NG
OK >> GO TO 11.
NG >> Repair harness or connector.
Te r m i n a l s
Condition Voltage (+)
(-)
ECM con-
nectorTe r m i n a l N o .
(Wire color)
F54 70 (B/W) Ground A/C switch: ON Approx. 0.36 - 3.88V
LJIA0124E
FRONT BLOWER CONTROL
DIAL ON: FAN ON SIG ON
FRONT BLOWER CONTROL
DIAL OFF: FAN ON SIG OFF
WJIA0469E
28 - 10 Continuity should exist.
WJIA0450E

ATC-120
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
11 . CHECK VOLTAGE FOR FRONT AIR CONTROL (FAN ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 10 (L/R) and ground.
OK or NG
OK >> GO TO 12.
NG-1 >> If the voltage is approx. 5V when blower motor is ON, replace front air control. Refer to ATC-147,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when blower motor is OFF, replace BCM. Refer to BCS-20, "
Removal
and Installation of BCM" .
12. CHECK CAN COMMUNICATION
Check CAN communication. Refer to LAN-5, "
CAN COMMUNICATION" .

BCM – ECM

ECM – IPDM E/R

ECM – Front air control
OK or NG
OK >> Inspection End.
NG >> Repair or replace malfunctioning part(s).
Terminals
Condition Voltage (+)
(-)
Front air con-
trol connectorTe r m i n a l N o .
(Wire color)
M49 10 (L/R) GroundA/C switch: ON
Blower motor
operatesApprox. 0V
A/C switch: OFF Approx. 5V
WJIA0451E