INFINITI QX56 2006 Factory Service Manual

ATC-60
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Operational Check (Rear)EJS003XM
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear blower control dial to switch position "1". Blower should operate on low speed.
2. Turn the rear blower control dial counterclockwise to switch position "2", "3", and "4" until all speeds are
checked.
3. Leave blower on MAX speed.
If NG, go to trouble diagnosis procedure for ATC-101, "
Rear Blower Motor Circuit" .
If OK, continue the check.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature and mode dial fully counterclockwise.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation if OK, go to trouble diagnosis procedure for ATC-121,
"Insufficient Cooling" . If air mix door motor appears to be malfunctioning, go to AT C - 7 9 , "DIAGNOSTIC PRO-
CEDURE FOR AIR MIX DOOR MOTOR (REAR)" .
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature and mode dial clockwise.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to trouble diagnosis procedure for ATC-128,
"Insufficient Heating" . If air mix door motor appears to be malfunctioning, go to AT C - 7 9 , "DIAGNOSTIC PRO-
CEDURE FOR AIR MIX DOOR MOTOR (REAR)" .
If OK, continue the check. Conditions : Engine running and at normal operating temperature

TROUBLE DIAGNOSISATC-61
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Revision: November 2009 2006 QX56
Power Supply and Ground Circuit for Front Air ControlEJS003XN
SYMPTOM: A/C system does not come on.
INSPECTION FLOW
*1AT C - 6 1 , "Power Supply and Ground
Circuit for Front Air Control". *2
ATC-58, "
Operational Check (Front)"
or AT C - 6 0 , "
Operational Check
(Rear)" .
WJIA1439E

ATC-62
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
COMPONENT DESCRIPTION
Front Air Control
The front air control has a built-in microcomputer which processes
information sent from various sensors needed for air conditioner
operation. The air mix door motors, mode door motor, intake door
motor, defroster door motor, blower motor and compressor are then
controlled.
The front air control is unitized with control mechanisms. When the
various switches and temperature dials are operated, data is input to
the front air control.
Self-diagnostic functions are also built into the front air control to pro-
vide quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
There are two PTCs (passenger and driver) built into the front air
control. They can be set at an interval of 0.5°C (1.0 °F) in the 16 °C
(60 °F) to 32 °C (90 °F) temperature range by rotating the temperature
dial. The set temperature is displayed.
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM
SYMPTOM: A/C system does not come on.
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Revision: November 2009 2006 QX56
1. CHECK POWER SUPPLY CIRCUITS FOR FRONT AIR CONTROL
1. Disconnect front air control connector.
2. Check voltage between front air control harness connector M49 terminals 14 and 22, and ground.
OK or NG
OK >> GO TO 2.
NG >> Check 10A fuses [Nos. 8 and 19, located in the fuse block (J/B)]. Refer to PG-76, "
FUSE BLOCK-
JUNCTION BOX (J/B)" .

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

If fuses are NG, replace fuse and check harness for short circuit. Repair or replace as neces-
sary.
2. CHECK GROUND CIRCUIT FOR FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Check continuity between front air control harness connector M49 terminal 1 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT
AIR CONTROL" .
NG >> Repair harness or connector.
Terminals Ignition switch position
(+)
(-) OFF ACC ON
Front air
control
connector Terminal No.
M49 14 GroundApprox. 0V Approx. 0V
Battery
voltage
M49 22 Battery
voltage Battery
voltage Battery
voltage
WJIA0415E
1 - Ground : Continuity should exist.
WJIA1351E

ATC-64
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Mode Door Motor CircuitEJS003XO
SYMPTOM:

Air outlet does not change.

Mode door motor does not operate normally.
INSPECTION FLOW
*1AT C - 3 0 , "Discharge Air Flow"*2AT C - 5 8 , "Operational Check
(Front)"
*3 AT C - 5 6 , "A/C System Self-diagnosis
Function"
*4 AT C - 5 7 , "SELF-DIAGNOSIS CODE
CHART"
*5AT C - 6 6 , "DIAGNOSTIC PROCE-
DURE FOR MODE DOOR
MOTOR"
*6 ATC-144, "FRONT AIR CONTROL"
*7 AT C - 3 9 , "SYMPTOM TABLE"
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Revision: November 2009 2006 QX56
SYSTEM DESCRIPTION
Component Parts
Mode door control system components are:

Front air control

Mode door motor

PBR (built into mode door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The mode door position (vent, B/L, foot, and defrost) is set by the front air control by means of the mode door
motor. When a mode door position is selected on the front air control, voltage is applied to one circuit of the
mode door motor while ground is applied to the other circuit, causing the mode door motor to rotate. The direc-
tion of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it.
The front air control monitors the mode door position by measuring the voltage signal on the PBR circuit.
In AUTO mode the mode door position is set by the front air control which determines the proper position
based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature
selected by the driver or passenger.
Mode Door Control Specification
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ATC-66
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
COMPONENT DESCRIPTION
Mode Door Motor
The mode door motor is attached to the heater & cooling unit. It
rotates so that air is discharged from the outlet as indicated by the
front air control. Motor rotation is conveyed to a link which activates
the mode door.
DIAGNOSTIC PROCEDURE FOR MODE DOOR MOTOR
1. CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the mode switch to the B/L ( ) mode.
3. Check voltage between front air control harness connector M49 terminal 5 and terminal 6 while pressing the mode switch to the
floor ( ) mode.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK MODE 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 5, 6 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
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Connector Terminals
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 6 5 Press
mode
switch Battery
voltage
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5 - Ground : Continuity should not exist.
6 - Ground : Continuity should not exist.
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Revision: November 2009 2006 QX56
3. CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the mode switch to the D/F ( ) mode.
2. Check voltage between front air control harness connector M49 terminal 5 and terminal 6 while pressing the mode switch to the
vent ( ) mode.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-144, "
FRONT AIR CONTROL" .
4. CHECK MODE 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 5 and terminal 6.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. CHECK MODE DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the mode door motor harness connector.
2. Check continuity between front air control harness connector M49 terminal 5, 6 and the mode door motor harness connector
terminal 5, 6.
OK or NG
OK >> Replace mode door motor. Refer to ATC-161, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
6. CHECK FRONT AIR CONTROL FOR PBR POWER AND GROUND
1. Reconnect front air control harness connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 2 and terminal 15.
OK or NG
OK >> GO TO 8.
NG >> GO TO 7.
Connector Terminals
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 5 6 Press
mode
switch Battery
voltage
WJIA1742E
Continuity should exist.
WJIA1728E
5 - 5 : Continuity should exist.
6 - 6 : Continuity should exist.
LJIA0027E
Connector Te r m i n a l s
Voltage
(Approx.)
(+) (-)
Front air control: M49 2 15 5V
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ATC-68
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
7. CHECK PBR REFERENCE VOLTAGE CIRCUIT 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 2 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
8. CHECK PBR REFERENCE VOLTAGE AND GROUND CIRCUITS
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 2 and terminal 15.
OK or NG
OK >> GO TO 10.
NG >> GO TO 9.
9. CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR OPEN
1. Disconnect the mode door motor harness connector.
2. Check continuity between mode door motor harness connector M142 (B) terminal 3, 1 and front air control harness connector
M49 (A) terminal 2, 15.
OK or NG
OK >> Replace mode door motor. Refer to ATC-161, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
10. CHECK PBR FEEDBACK VOLTAGE
1. Reconnect the front air control harness connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 16 and ground while cycling mode switch through all
modes.
OK or NG
OK >> GO TO 12.
NG >> GO TO 11. Continuity should not exist.
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Continuity should exist.
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2 - 3
: Continuity should exist.
15 - 1 : Continuity should exist.
WJIA1732E
Voltage : Approx. 1V - 4.5V
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TROUBLE DIAGNOSISATC-69
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Revision: November 2009 2006 QX56
11 . CHECK PBR FEEDBACK SIGNAL CIRCUIT FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 16 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
12. CHECK PBR FEEDBACK CIRCUIT FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the mode door motor harness connector and front air control harness connector.
3. Check continuity between mode door motor harness connector M142 terminal 2 and front air control harness connector M49 ter-
minal 16.
OK or NG
OK >> Replace mode door motor. Refer to ATC-161, "Removal
and Installation" .
NG >> Repair or replace harness as necessary. Continuity should not exist.
WJIA1733E
Continuity should exist.
LJIA0034E