2006 INFINITI QX56 heater

ATC-3
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Revision: November 2009 2006 QX56
DIAGNOSTIC PROCEDURE FOR IN-VEHICLE
SENSOR ..........................................................
. 138
COMPONENT INSPECTION ........................... . 140
Optical Sensor Circuit ......................................... . 140
COMPONENT DESCRIPTION ........................ . 140
OPTICAL INPUT PROCESS ........................... . 140
DIAGNOSTIC PROCEDURE FOR OPTICAL
SENSOR .......................................................... . 141
Intake Sensor Circuit ........................................... . 142
COMPONENT DESCRIPTION ........................ . 142
DIAGNOSTIC PROCEDURE FOR INTAKE SEN-
SOR ................................................................. . 142
COMPONENT INSPECTION ........................... . 143
CONTROL UNIT .................................................... . 144
Removal and Installation ..................................... . 144
FRONT AIR CONTROL ................................... . 144
REAR AIR CONTROL ...................................... . 144
AMBIENT SENSOR ............................................... . 145
Removal and Installation ..................................... . 145
REMOVAL ........................................................ . 145
INSTALLATION ................................................ . 145
IN-VEHICLE SENSOR ........................................... . 146
Removal and Installation ..................................... . 146
REMOVAL ........................................................ . 146
INSTALLATION ................................................ . 146
OPTICAL SENSOR ............................................... . 147
Removal and Installation ..................................... . 147
INTAKE SENSOR .................................................. . 148
Removal and Installation ..................................... . 148
REMOVAL ........................................................ . 148
INSTALLATION ................................................ . 148
BLOWER MOTOR ................................................. . 149
Components ........................................................ . 149
Removal and Installation ..................................... . 149
FRONT BLOWER MOTOR .............................. . 149
REAR BLOWER MOTOR ................................ . 150
IN-CABIN MICROFILTER ...................................... . 151
Removal and Installation ..................................... . 151
FUNCTION ....................................................... . 151
REPLACEMENT TIMING ................................. . 151
REPLACEMENT PROCEDURE ...................... . 151
HEATER & COOLING UNIT ASSEMBLY ............. . 153
Components ........................................................ . 153
Removal and Installation ..................................... . 154
FRONT HEATER AND COOLING UNIT ASSEM-
BLY ................................................................... . 154
REAR HEATER AND COOLING UNIT ASSEM-
BLY ................................................................... . 155
HEATER CORE ..................................................... . 156
Components ........................................................ . 156
Removal and Installation ..................................... . 157
FRONT HEATER CORE .................................. . 157
REAR HEATER CORE .................................... . 158
DEFROSTER DOOR MOTOR ............................... . 159
Removal and Installation ..................................... . 159
REMOVAL ........................................................ . 159
INSTALLATION ................................................ . 159INTAKE DOOR MOTOR ........................................
.160
Removal and Installation ..................................... .160
REMOVAL ........................................................ .160
INSTALLATION ................................................ .160
MODE DOOR MOTOR ........................................... .161
Removal and Installation ..................................... .161
REMOVAL ........................................................ .161
INSTALLATION ................................................ .161
AIR MIX DOOR MOTOR ........................................ .162
Components ........................................................ .162
Removal and Installation ..................................... .162
FRONT AIR MIX DOOR MOTOR (DRIVER) .... .162
FRONT AIR MIX DOOR MOTOR (PASSENGER) .163
REAR AIR MIX DOOR MOTOR ....................... .163
VARIABLE BLOWER CONTROL .......................... .164
Removal and Installation ..................................... .164
REMOVAL ........................................................ .164
INSTALLATION ................................................ .164
REAR BLOWER MOTOR RESISTOR ................... .165
Removal and Installation ..................................... .165
REMOVAL ........................................................ .165
INSTALLATION ................................................ .165
DUCTS AND GRILLES .......................................... .166
Components ........................................................ .166
Removal and Installation ..................................... .169
CENTER CONSOLE HEAT DUCT AND REAR
FINISHER ASSEMBLY GRILLE ....................... .169
DEFROSTER NOZZLE .................................... .169
RH AND LH SIDE DEMISTER DUCT .............. .169
RH AND LH VENTILATOR DUCT .................... .169
CENTER VENTILATOR DUCT ........................ .169
FLOOR DUCT .................................................. .169
REAR OVERHEAD DUCTS ............................. .170
REAR FLOOR DUCT ....................................... .170
GRILLES .......................................................... .170
REFRIGERANT LINES .......................................... .171
HFC-134a (R-134a) Service Procedure .............. .171
SETTING OF SERVICE TOOLS AND EQUIP-
MENT ............................................................... .171
Components ........................................................ .173
Removal and Installation for Compressor ........... .175
REMOVAL ........................................................ .175
INSTALLATION ................................................ .176
Removal and Installation for Compressor Clutch . 176 REMOVAL ........................................................ .176
INSPECTION ................................................... .177
INSTALLATION ................................................ .177
BREAK-IN OPERATION ................................... .179
Removal and Installation for Low-pressure Flexible
Hose .................................................................... .179
REMOVAL ........................................................ .179
INSTALLATION ................................................ .179
Removal and Installation for High-pressure Flexible
Hose .................................................................... .179
REMOVAL ........................................................ .179
INSTALLATION ................................................ .179
Removal and Installation for High-pressure Pipe . 179 REMOVAL ........................................................ .179
INSTALLATION ................................................ .179

ATC-4Revision: November 20092006 QX56
Removal and Installation for Low-pressure Pipe .
.180
REMOVAL ........................................................ .180
INSTALLATION ................................................. .180
Removal and Installation for Rear High- and Low-
pressure A/C and Heater Core Pipes .................. .180
REMOVAL ........................................................ .180
INSTALLATION ................................................. .181
Removal and Installation for Underfloor Rear High-
and Low-pressure A/C and Heater Core Pipes ... .181
REMOVAL ........................................................ .181
INSTALLATION ................................................. .182
Removal and Installation for Refrigerant Pressure
Sensor ................................................................. .182
REMOVAL ........................................................ .182
INSTALLATION ................................................. .182
Removal and Installation for Condenser .............. .182
REMOVAL ........................................................ .182
INSTALLATION ................................................. .183
Removal and Installation for Front Evaporator .... .184
REMOVAL ........................................................ .184
INSTALLATION ................................................. .185
Removal and Installation for Rear Evaporator ..... .185
REMOVAL ........................................................ .186INSTALLATION .................................................
.186
Removal and Installation for Front Expansion Valve .186
REMOVAL ......................................................... .186
INSTALLATION ................................................. .186
Removal and Installation for Rear Expansion Valve .186
REMOVAL ......................................................... .186
INSTALLATION ................................................. .187
Checking for Refrigerant Leaks ........................... .187
PRELIMINARY CHECK .................................... .187
Checking System for Leaks Using the Fluorescent
Dye Leak Detector ............................................... .187
Dye Injection ........................................................ .187
Electronic Refrigerant Leak Detector ................... .188
PRECAUTIONS FOR HANDLING LEAK
DETECTOR ...................................................... .188
CHECKING PROCEDURE ............................... .189
SERVICE DATA AND SPECIFICATIONS (SDS) ... .191
Service Data and Specifications (SDS) ............... .191
COMPRESSOR ................................................ .191
OIL .................................................................... .191
REFRIGERANT ................................................ .191
ENGINE IDLING SPEED .................................. .191
BELT TENSION ................................................ .191

PRECAUTIONSATC-9
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Revision: November 2009 2006 QX56
Rear A/C
1. High-pressure service valve 2. Grommet3. High-pressure pipe
4. Refrigerant pressure sensor 5. Condenser 6. Compressor shaft seal
7. High-pressure flexible hose 8. Low-pressure flexible hose 9. Low-pressure service valve
10. Low-pressure pipe 11. Expansion valve (front)12. Drain hose
WJIA2315E
1. Rear heater and cooling unit assembly 2. Rear A/C pipes 3. Rear A/C heater core pipes
4. Rear heater core hose 5. Rear blower motor6. Underfloor rear A/C pipes
7. Underfloor rear heater core pipes A. Bolt torque specifications B. Leak checking order (l - r)
C. Tightening torque D. Wrench sizeE. O-ring size
⇐ Front
NOTE: The O-ring size 8 is the high-side and the O-ring size 16 is the low-side.

REFRIGERATION SYSTEMATC-21
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Revision: November 2009 2006 QX56
REAR REFRIGERATION SYSTEM
1. Defroster nozzle2. LH side demister duct3. LH ventilator duct
4. RH side demister duct 5. RH ventilator duct6. Center ventilator duct
7. Front heater and cooling unit assembly 8. Floor duct 9. Clips
10. Heat duct
1. Rear floor duct 2. Rear heater and cooling unit assembly 3. Rear lower overhead duct
4. Rear upper overhead duct
LJIA0142E

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.
WJIA0587E
Connector Terminals
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

ATC-72
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
COMPONENT DESCRIPTION
Air Mix Door Motors
The driver (1) and front passenger (2) air mix door motors are
attached to the front heater & cooling unit assembly. The rear air mix
door motor is attached to the rear heater & cooling unit. These
motors rotate so that the air mix door is opened or closed to a posi-
tion set by the front (or rear) air control. Motor rotation is then con-
veyed through a shaft and the air mix door position is then fed back
to the front air control by the PBR built into the air mix door motors.
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR (DRIVER)
1. CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Rotate temperature control dial (driver) to 32° C (90°F).
3. Check voltage between front air control harness connector M49 terminal 3 and terminal 4 while rotating temperature control dial
(driver) to 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK AIR MIX DOOR MOTOR (DRIVER) 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 3, 4 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
WJIA2309E
WJIA1245E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 3 4 Rotate temp
control dial Battery
voltage
WJIA1735E
3 - Ground : Continuity should not exist.
4 - Ground : Continuity should not exist.
WJIA1736E

ATC-88
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
SYSTEM DESCRIPTION
Component Parts
Defroster door control system components are:

Front air control

Defroster door motor

PBR (Built into defroster door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The front air control determines defroster door position based 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 motor rotates in the opposite direction closing off air flow
to the defroster ducts.
In the AUTO mode, the front air control determines defroster 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 front air control 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.
WJIA1354E
WJIA0592E

ATC-132
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Water Valve CircuitEJS003Y1
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 front air control.
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 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 1 and front air control harness connector M50 (B)
terminal 29.
4. Check continuity between water valve harness connector F68 (A) terminal 1 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
NG >> Repair harness or connector.
WJIA1791E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 1 2Rotate temperature
control dial Battery
voltage
WJIA1792E
1 - 29 : Continuity should exist.
1 - Ground : Continuity should not exist.
WJIA1793E