2010 INFINITI QX56 heater

HIGH-PRESSURE PIPEHA-43
< ON-VEHICLE REPAIR >
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5. Remove the front and rear bumper fascia. Refer to EXT-13, "Removal and Installation" (front), EXT-15,
"Removal and Installation" (rear).
6. Reposition the front fender protector out of the way. Refer to EXT-23, "
Removal and Installation".
7. Disconnect the chassis harness connector.
8. Remove the spare wheel and tire.
9. Remove the tailpipe and tailpipe hanger bracket. Refer to EX-6, "
Removal and Installation".
10. Remove the seatbelt latch anchor. Refer to EX-6, "
Removal and Installation".
11. Remove the front floor heat shield.
12. Disconnect each end of the underfloor rear high- and low-pressure A/C and heater core pipes. Refer to HA-29, "
Component".
CAUTION:
Cap or wrap the joint of the pipes with suitable material such as viny l tape to avoid the entry of air.
13. Set two suitable jacks at the RH body mount points to support the vehicle body when it is separated from the RH side of the frame.
14. Remove the RH body mount bolts. Refer to BRM-6, "
Body Mounting".
15. Use the vehicle hoist to lower the RH side of the frame from the RH side of the body [approximately 305 mm (12 in)] until there is sufficient clearance to remove the underfloor rear high- and low-pressure A/C
and heater core pipes from between the body and the frame.
16. Remove the underfloor rear high- and low-pressure A/C and heater core pipes from the back of the vehi- cle.
INSTALLATION
Installation is in the reverse order of removal.
CAUTION:
• Replace the O-rings of the underfloor rear high - and low-pressure A/C and heater core pipes with
new ones, then apply compressor oil to them for installation.
• After charging refrigerant, check for leaks.
Revision: April 20092010 QX56

HAC-1
VENTILATION, HEATER & AIR CONDITIONER
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CONTENTS
HEATER & AIR CONDITIONING CONTROL SYSTEM
AUTOMATIC AIR CONDITIONER
BASIC INSPECTION ....... .............................
3
DIAGNOSIS AND REPAIR WORKFLOW ..... .....3
How to Perform Trouble Diagnosis For Quick And
Accurate Repair ........................................................
3
INSPECTION AND ADJUSTMENT ................ .....4
Operational Check (Front) ................................... ......4
Operational Check (Rear) .........................................5
FUNCTION DIAGNOSIS ...............................7
FUNCTION INFORMATION ........................... .....7
Component Part Location ................................... ......7
Symptom Table .........................................................9
REFRIGERATION SYSTEM ..............................11
Refrigerant Cycle ................................................ ....11
Refrigerant System Protection ................................11
AUTOMATIC AIR CONDITIONER SYSTEM . ....13
Control System Diagram ..................................... ....13
Control System Description .....................................13
Discharge Air Flow (Front) ......................................16
Discharge Air Flow (Rear) .......................................16
Switches And Their Control Function (Front) ..........18
Switches And Their Control Function (Rear) ...........19
DIAGNOSIS SYSTEM (HVAC) ..........................20
CONSULT-III Function (HVAC) ........................... ....20
DIAGNOSIS SYSTEM (BCM) ............................21
CONSULT-III Function (BCM - COMMON ITEM) ....21
CONSULT-III Function (BCM - AIR CONDITION-
ER) ...................................................................... ....
21
SELF-DIAGNOSIS FUNCTION ..........................23
A/C Auto Amp. Self-Diagnosis ................................23
A/C and AV Switch Asse mbly Self-Diagnosis .........23
A/C System Self-Diagnosis Code Chart .............. ....24
COMPONENT DIAGNOSIS .........................25
MODE DOOR MOTOR ......................................25
System Description .............................................. ....25
Mode Door Motor (Front) Component Function
Check ......................................................................
26
Mode Door Motor (Front) Diagnosis Procedure ......26
AIR MIX DOOR MOTOR ...................................30
System Description ..................................................30
Air Mix Door Motor (Driver) Component Function
Check ......................................................................
31
Air Mix Door Motor (Driver) Diagnosis Procedure ....32
Air Mix Door Motor (Passenger) Component
Function Check ........................................................
35
Air Mix Door Motor (Passenger) Diagnosis Proce-
dure .........................................................................
35
INTAKE DOOR MOTOR ...................................39
System Description ..................................................39
Intake Door Motor Component Function Check ......40
Intake Door Motor Diagnosis Procedure .................40
DEFROSTER DOOR MOTOR CIRCUIT ...........42
System Description ..................................................42
Defroster Door Motor Component Function Check
....
43
Defroster Door Motor Diagnosis Procedure ............43
BLOWER MOTOR CONTROL SYSTEM ..........47
System Description ..................................................47
Front Blower Motor Component Function Check ....48
Front Blower Motor Diagnosis Procedure ................48
Front Blower Motor Component Inspection .............52
Rear Blower Motor Description ................................53
Rear Blower Motor Component Function Check .....53
Rear Air Control (Front) Diagnosis Procedure #1 ....54
Rear Air Control (Rear) Diagnosis Procedure #2 ....56
Rear Blower Motor Component Inspection ..............57
REAR AIR CONTROL SYSTEM .......................58
Rear Air Control System Description .......................58
Revision: April 20092010 QX56

HAC-26
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
MODE DOOR MOTOR
The mode door motor (front) is attached to the heater & cooling unit
assembly. It rotates so that air is discharged from the outlet as indi-
cated by the A/C auto amp. Motor rotation is conveyed to a link
which activates the mode door.
Mode Door Motor (Front)
Component Function CheckINFOID:0000000005147688
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 HAC-16, "
Discharge
Air Flow (Front)".
NOTE:
Confirm that the compressor clutch is engaged (visual inspection) and intake door position is at FRESH
when DEF ( ) or D/F ( ) is selected.
Is the inspection result normal?
YES >> Inspection End.
NO >> Go to diagnosis procedure. Refer to HAC-26, "
Mode Door Motor (Front) Diagnosis Procedure".
Mode Door Motor (Front) Diagnosis ProcedureINFOID:0000000005147689
Regarding Wiring Diagram information, refer to HAC-91, "Wiring Diagram".
SYMPTOM:• Air outlet does not change.
• Mode door motor does not operate normally.
1.CHECK A/C AUTO AMP. FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the mode switch to the B/L ( ) mode.
3. Check voltage between A/C auto amp. harness connector M49 terminal 19 and terminal 20 while pressing the mode switch to
the floor ( ) mode.
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK MODE DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
WJIA0587E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
A/C auto amp.: M49 20
19Press
mode
switch Battery
voltage
AWIIA0095ZZ
Revision: April 20092010 QX56

AIR MIX DOOR MOTORHAC-31
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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Air Mix Door Control Specification
COMPONENT DESCRIPTION
Air Mix Door Motors (front)
The driver (1) and passenger (2) air mix door motors are attached to
the front heater & cooling unit assembly. These motors rotate so that
the air mix door is opened or closed to a position set by the A/C auto
amp. Motor rotation is then conveyed through a shaft and the air mix
door position is then fed back to t
he A/C auto amp. by the PBR built
into the air mix door motors.
Air Mix Door Motor (rear)
The air mix door motor (rear) (1) is attached to the rear heater &
cooling unit assembly. These motors rotate so that the air mix door is
opened or closed to a position set by the front (or rear) air control.
Motor rotation is then conveyed through a shaft and the air mix door
position is then fed back to the A/C auto amp. by the PBR built into
the air mix door motors.
Air Mix Door Motor (Driver) Component Function CheckINFOID:0000000005147691
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 18° C (60°F) is displayed.
2. Check for cold air at discharge air outlets.
Is the inspection result normal?
YES >> Inspection End.
NO >> Go to diagnosis procedure. Refer to HAC-32, "
Air Mix Door Motor (Driver) Diagnosis Procedure".
AWIIA0107GB
AWIIA0109ZZ
AWIIA0111ZZ
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HAC-42
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
DEFROSTER DOOR MOTOR CIRCUIT
DEFROSTER DOOR
MOTOR CIRCUIT
System DescriptionINFOID:0000000005147697
SYSTEM DESCRIPTION
Component Parts
Defroster door control system components are:• A/C auto amp.
• A/C and AV switch assembly
• Defroster door motor
• PBR (Built into defroster door motor)
• In-vehicle sensor
• Ambient sensor
• Optical sensor
• Intake sensor
System Operation
The A/C auto amp. determines defroster door position bas ed on the position of the defroster switch. When the
defroster switch is depressed, the defroster door motor rotates directing air to the defroster ducts. When any
mode other than defroster is selected, the defroster moto r rotates in the opposite direction closing off air flow
to the defroster ducts.
In the AUTO mode, the A/C auto amp. determines def roster door position based on the ambient temperature,
the intake air temperature and the in-vehicle temperature.
COMPONENT DESCRIPTION
Defroster door motor
The defroster door motor is attached to the front heater & cooling
unit assembly. The A/C auto amp. sends a voltage to rotate to the
defroster door directing the air flow either to the defroster ducts, or to
the floor ducts, depending on which way the voltage and ground are
applied to the motor leads. Motor rotation is conveyed to a lever
which activates the defroster door.
AWIIA0151GB
WJIA0592E
Revision: April 20092010 QX56

WATER VALVE CIRCUITHAC-73
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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WATER VALVE CIRCUIT
DescriptionINFOID:0000000005147716
COMPONENT DESCRIPTION
Water Valve
The water valve (1) cuts the flow of engine coolant to the front and
rear heater cores to allow for maximum cooling during A/C opera-
tion. It is controlled by the A/C auto amp.
Water Valve Diagnosis ProcedureINFOID:0000000005147717
Regarding Wiring Diagram information, refer to HAC-91, "Wiring Diagram".
DIAGNOSTIC PROCEDURE FOR WATER VALVE
1.CHECK WATER VALVE POWER AND GROUND CIRCUITS
1. Disconnect water valve connector F68.
2. Turn ignition switch ON.
3. Rotate temperature control dial (driver) to 32 °C (90 °F).
4. Check voltage between water valve harness connector F68 ter- minal 1 and terminal 2 while rotating temperature control dial
(driver) to 18 °C (60° F).
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/C auto amp. connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 2 and A/C auto amp. harness connector M50 (B)
terminal 46.
4. Check continuity between water valve harness connector F68 terminal 2 and ground.
Is the inspection result normal?
YES >> Replace A/C auto amp. Refer to VTL-7, "Removal and Installation".
NO >> Repair harness or connector.
WJIA1791E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 2 1Rotate temperature
control dial Battery
voltage
WJIA1794E
2 - 46 : Continuity should exist.
2 - Ground : Continuity should not exist.
AWIIA0203ZZ
Revision: April 20092010 QX56

INTAKE SENSORHAC-83
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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INTAKE SENSOR
System DescriptionINFOID:0000000005147726
COMPONENT DESCRIPTION
Intake Sensor
The intake sensor is located on the heater & cooling unit assembly. It
converts temperature of air after if passes through the evaporator
into a resistance value which is then input to the A/C auto amp.
Intake Sensor Diagnosis ProcedureINFOID:0000000005147727
Regarding Wiring Diagram information, refer to HAC-91, "Wiring Diagram".
DIAGNOSTIC PROCEDURE FOR INTAKE SENSOR
SYMPTOM: Intake sensor circuit is open or shorted. Using the CON-
SULT-III, DTC B2581 or B2582 is displayed. Without a CONSULT-III,
code 56 or 57 is indicated on A/C auto amp. as a result of conducting
self-diagnosis.
1.CHECK VOLTAGE BETWEEN INTAKE SENSOR AND GROUND
1. Disconnect intake sensor connector.
2. Turn ignition switch ON.
3. Check voltage between intake sensor harness connector M146 terminal 2 and ground.
Is the inspection result normal?
YES >> GO TO 2.
NO >> GO TO 4.
2.CHECK CIRCUIT CONTINUITY BETWEEN INTAKE SENSOR AND A/C AUTO AMP.
WJIA0571E
AWIIA0208GB
2 - Ground : Approx. 5V
WJIA1375E
Revision: April 20092010 QX56

HAC-116
< SYMPTOM DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
INSUFFICIENT HEATING
INSUFFICIENT HEATING
Component Function CheckINFOID:0000000005147739
SYMPTOM: Insufficient heating
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPER
ATIONAL CHECK - TEMPERATURE INCREASE
1. Press the AUTO switch.
2. Turn the temperature control dial (driver) clockwise until 32 °C (90° F) is displayed.
3. Check for hot air at discharge air outlets.
Can this symptom be duplicated?
YES >> GO TO 2.
NO >> Perform complete system operational check. Refer to HAC-4, "
Operational Check (Front)".
2.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 3.
3.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis. Refer to HAC-23, "
A/C Auto Amp. Self-Diagnosis".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Refer to HAC-24, "
A/C System Self-Diagnosis Code Chart".
4.CHECK ENGINE COOLING SYSTEM
1. Check for proper engine coolant level. Refer to CO-10, "
Inspection".
2. Check hoses for leaks or kinks.
3. Check radiator cap. Refer to CO-10, "
Inspection".
4. Check for air in cooling system.
>> GO TO 5.
5.CHECK AIR MIX DOOR OPERATION
Check the operation of the air mix door.
Is the inspection result normal?
YES >> GO TO 6.
NO >> Check the air mix door motor circuit. Refer to HAC-31, "
Air Mix Door Motor (Driver) Component
Function Check".
6.CHECK AIR DUCTS
Check for disconnected or leaking air ducts.
Is the inspection result normal?
YES >> GO TO 7.
NO >> Repair all disconnected or leaking air ducts.
7.CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses. The inlet hose should be hot and the outlet hose should be
warm.
Is the inspection result normal?
YES >> Hot inlet hose and a warm outlet hose: GO TO 8.
NO >> • Inlet hose cold: GO TO 11. • Both hoses warm: GO TO 9.
8.CHECK ENGINE COOLANT SYSTEM
Revision: April 20092010 QX56