INFINITI QX56 2007 Factory Service Manual

TROUBLE DIAGNOSISATC-51
< SERVICE INFORMATION >
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1. Rotate temperature control dial (driver si de or passenger side) counterclockwise until 16 °C (60 °F) is dis-
played.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operat ion. If OK, go to trouble diagnosis procedure for ATC-100,
"Insufficient Cooling" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" or ATC-59, "Air Mix Door Motor Circuit".
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockw ise (driver side or passenger side) until 32°C (90 °F) is displayed.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operat ion. If OK, go to trouble diagnosis procedure for ATC-108,
"Insufficient Heating" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" or ATC-59, "Air Mix Door Motor Circuit".
If OK, continue with next check.
CHECK A/C SWITCH
1. Press A/C switch when AUTO switch is ON, or in manual mode.
2. A/C switch indicator will turn ON.
• Confirm that the compressor clutch engages (sound or visual inspection).
NOTE:
If current mode setting is DEF or D/F, compressor clutch may already be engaged.
If NG, go to trouble diagnosis procedure for ATC-96, "
Magnet Clutch Circuit" .
If OK, continue with next check.
CHECKING AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO.
• If ambient temperature is warm, and selected temperat ure is cool, confirm that the compressor clutch
engages (sound or visual inspection). (Discharge air and blower speed will depend on ambient, in-vehi-
cle, and set temperatures.)
If NG, go to trouble diagnosis procedure for ATC-52, "
Power Supply and Ground Circuit for Front Air Control" ,
then if necessary, trouble diagnosis procedure for ATC-96, "
Magnet Clutch Circuit" .
If all operational checks are OK (symptom cannot be duplicated), go to malfunction Simulation Tests in AT C -
32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" and perform tests as outlined to simu-
late driving conditions environment . If symptom appears. Refer to ATC-32, "
How to Perform Trouble Diagnosis
for Quick and Accurate Repair", ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair"
and perform applicable trouble diagnosis procedures.
Operational Check (Rear)INFOID:0000000003533250
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear blower control dial to swit ch position "1". Blower should operate on low speed.
2. Turn the rear blower control dial counterclockwis e 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-85, "
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. Conditions : Engine running and at normal operating temperature

ATC-52
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
If NG, listen for sound of air mix door motor operation if OK, go to trouble diagnosis procedure for ATC-100,
"Insufficient Cooling" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit".
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 operat ion. If OK, go to trouble diagnosis procedure for ATC-108,
"Insufficient Heating". If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" .
If OK, continue the check.
Power Supply and Ground Circu it for Front Air ControlINFOID:0000000003533251
SYMPTOM: A/C system does not come on.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO. Confirm that the compressor clutch engages (sound or visual inspection).
(Discharge air and blower speed will depend on am bient, in-vehicle and set temperatures.)
Can a symptom be duplicated?
YES >> GO TO 3.
NO >> GO TO 2.
2.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Refer to ATC-50, "
Operational Check
(Front)".
Can a symptom be duplicated
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair".
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK POWER AND GROUND CIRCUIT
Check main power supply and ground circuit. Refe r to "DIAGNOSTIC PROCEDURE FOR A/C SYSTEM".
OK or NG
OK >> System OK.
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
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.
WJIA0544E

TROUBLE DIAGNOSISATC-53
< SERVICE INFORMATION >
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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.
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-73
.
• If fuses are OK, check harness for open circuit. Repair or replace as necessary.
• If fuses are NG, replace fuse and check harness fo r short circuit. Repair or replace as neces-
sary.
2.CHECK GROUND CIRCUIT FOR FRONT AIR CONTROL
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Terminals Ignition switch position
(+)
(-) OFF ACC ON
Front air
control
connector Te r m i n a l N o .
M49 14 GroundApprox. 0V Approx. 0V
Battery
voltage
M49 22 Battery
voltage Battery
voltage Battery
voltage
WJIA0415E

ATC-54
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Check continuity between front air control harness connectorM49 terminal 1 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair harness or connector.
Mode Door Motor CircuitINFOID:0000000003533252
SYMPTOM:
• Air outlet does not change.
• Mode door motor does not operate normally.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OP ERATIONAL CHECK - DISCHARGE AIR
1. Press mode switch four times and then press the (DEF) switch. Each position indicator should change shape (on display).
2. Confirm that discharge air comes out according to the air distribution table. Refer to ATC-26, "
Discharge
Air Flow".
NOTE:
Confirm that the compressor clutch is engaged (visual inspection) and intake door position is at FRESH
when DEF ( ) or D/F ( ) is selected.
Can a symptom be duplicated?
YES >> GO TO 3.
NO >> GO TO 2.
2.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Refer to ATC-50, "
Operational Check
(Front)".
Can a symptom be duplicated?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair".
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK MODE DOOR OPERATION
Check and verify mode door mechanism for smooth operation in each mode.
OK or NG
OK >> GO TO 5.
NG >> Repair as necessary.
5.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to ATC-48, "
A/C System Self-Diagnosis Function".
Are any self-diagnosis codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function".
NO >> GO TO 6.
6.CHECK THE MODE DOOR MOTOR PBR CIRCUIT 1 - Ground : Continuity should exist.
WJIA1351E

TROUBLE DIAGNOSISATC-55
< SERVICE INFORMATION >
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Perform diagnostic procedure for the mode door moto r. Refer to "DIAGNOSTIC PROCEDURE FOR MODE
DOOR MOTOR".
OK or NG
OK >> GO TO 7.
NG >> Repair PBR circuit or replace motor.
7.RECHECK FOR CODES
Perform self-diagnosis. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
Are any self-diagnostic codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function" .
NO >> GO TO 8.
8.RECHECK FOR SYMPTOMS
Perform a complete operational check and check for any symptoms. Refer to ATC-50, "
Operational Check
(Front)" .
Does another symptom exist?
YES >> Repair as necessary.
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation" .
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 se t 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 circui t, 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 positi on by measuring the voltage signal on the PBR circuit.
In AUTO mode the mode door position is set by the fr ont air control which determines the proper position
based on inputs from the in-vehicle sens or, ambient sensor, optical sensor, intake sensor, and the temperature
selected by the driver or passenger.
WJIA1240E

ATC-56
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Mode Door Control Specification
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-123, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR GROUND AND POWER
WJIA0434E
WJIA0587E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 6 5 Press
mode
switch Battery
voltage
WJIA1727E
5 - Ground : Continuity should not exist.
6 - Ground : Continuity should not exist.
WJIA1734E

TROUBLE DIAGNOSISATC-57
< SERVICE INFORMATION >
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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-123, "
Removal and Installation" .
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-140, "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.
7.CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 5 6 Press
mode
switch Battery
voltage
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Continuity should exist.
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5 - 5 : Continuity should exist.
6 - 6 : Continuity should exist.
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Connector Te r m i n a l s
Voltage (Ap-
prox.)
(+) (-)
Front air control: M49 2 15 5V
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ATC-58
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connectorM49 terminal 2 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
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 VO LTAGE 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-140, "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.
11 .CHECK PBR FEEDBACK SIGNAL CIRCUIT FOR SHORT TO GROUND Continuity should not exist.
WJIA1730E
Continuity should exist.
WJIA1731E
2 - 3 : Continuity should exist.
15 - 1 : Continuity should exist.
WJIA1732E
Voltage : Approx. 1V - 4.5V
LJIA0032E

TROUBLE DIAGNOSISATC-59
< SERVICE INFORMATION >
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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-123, "Removal
and Installation" .
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-140, "Removal
and Installation".
NG >> Repair or replace harness as necessary.
Air Mix Door Motor CircuitINFOID:0000000003533253
SYMPTOM:• Discharge air temperature does not change.
• Air mix door motor does not operate.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERAT IONAL CHECK - TEMPERATURE INCREASE
1. Turn the temperature control dial (driver) clockwise until 32 °C (90 °F) is displayed.
2. Check for hot air at discharge air outlets.
>> GO TO 2.
2.CONFIRM SYMPTOM BY PERFORMING OPERAT IONAL CHECK - TEMPERATURE DECREASE
1. Turn the temperature control dial (driver) counterclockwise until 16 °C (60 °F) is displayed.
2. Check for cold air at discharge air outlets.
Can a symptom be duplicated?
YES >> GO TO 4.
NO >> GO TO 3.
3.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Refer to ATC-50, "
Operational Check
(Front)" .
Can a symptom be duplicated?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" .
NO >> System OK.
4.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 5.
Continuity should not exist.
WJIA1733E
Continuity should exist.
LJIA0034E

ATC-60
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
5.CHECK AIR MIX DOOR OPERATION
Check and verify air mix door mechanism for smooth operation from 16 °C (60 °F) to 32 °C (90 °F) in each
mode.
OK or NG
OK >> GO TO 6.
NG >> Repair as necessary.
6.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
Are any self-diagnosis codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function" .
NO >> GO TO 7.
7.CHECK THE AIR MIX DOOR MOTOR PBR CIRCUIT
Perform diagnostic procedure for the air mix door motors. Refer to "Air Mix Door Motor Circuit" .
OK or NG
OK >> GO TO 8.
NG >> Repair PBR circuit or replace air mix door motor. Refer to ATC-141
.
8.RECHECK FOR CODES
Perform self-diagnosis. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
Are any self-diagnostic codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function" .
NO >> GO TO 9.
9.RECHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to ATC-50, "
Operational Check (Front)".
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" .
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
SYSTEM DESCRIPTION
Component Parts
Air mix door control system components are:
• Front air control.
• Air mix door motors (Driver, Passenger, and rear)
• PBR (built-into air mix door motors)
• In-vehicle sensor
• Ambient sensor
• Optical sensor
• Intake sensor
System Operation
The front air control receives data from the temperatur e selected by the driver side, passenger side, and rear.
The front air control then applies a voltage to one circuit of the appropriate air mix door motor, while ground is
applied to the other circuit, causing the appropriate air mix door motor to rotate. The direction of rotation is
determined by which circuit has voltage applied to it, and which one has ground applied to it. The front air con-
trol monitors the air mix door positions by measur ing the voltage signal on the PBR circuits of each door.
In AUTO mode the air mix, intake, mode door, and defrost door positions are 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 and front and rear passengers.