2007 INFINITI QX56 heater

ATC-2
Removal and Installation .......................................126
INTAKE SENSOR ............................................127
Removal and Installation ..................................... ..127
BLOWER MOTOR ...........................................128
Component .......................................................... ..128
Removal and Installation .......................................128
IN-CABIN MICROFILTER ................................130
Removal and Installation ..................................... ..130
HEATER & COOLING UNIT ASSEMBLY .......132
Component .......................................................... ..132
Removal and Installation .......................................133
HEATER CORE ...............................................135
Component .......................................................... ..135
Removal and Installation .......................................136
DEFROSTER DOOR MOTOR .........................138
Removal and Installation ..................................... ..138
INTAKE DOOR MOTOR ..................................139
Removal and Installation ..................................... ..139
MODE DOOR MOTOR ....................................140
Removal and Installation ..................................... ..140
AIR MIX DOOR MOTOR ..................................141
Component .......................................................... ..141
Removal and Installation .......................................141
VARIABLE BLOWER CONTROL ...................143
Removal and Installation ..................................... ..143
REAR BLOWER MOTOR RESISTOR ............144
Removal and Installation ..................................... ..144
DUCTS AND GRILLES ....................................145
Component .......................................................... .145
Removal and Installation .......................................148
REFRIGERANT LINES ................................... ..150
HFC-134a (R-134a) Service Procedure ............... .150
Component ...........................................................152
Removal and Installation for Compressor .............154
Removal and Installation for Compressor Clutch ..155
Removal and Installation for Low-Pressure Flexi-
ble Hose ............................................................... .
158
Removal and Installation for High-pressure Flexi-
ble Hose ............................................................... .
158
Removal and Installation for High-pressure Pipe ..158
Removal and Installation for Low-Pressure Pipe ..159
Removal and Installation for Rear High- and Low-
Pressure A/C and Heater Core Pipes .................. .
159
Removal and Installation for Underfloor Rear
High- and Low-Pressure A/C and Heater Core
Pipes .................................................................... .
160
Removal and Installation for Refrigerant Pressure
Sensor .................................................................. .
161
Removal and Installation for Condenser ...............161
Removal and Installation for Front Evaporator .....163
Removal and Installation for Rear Evaporator ......164
Removal and Installation for Front Expansion
Valve .....................................................................
165
Removal and Installation for Rear Expansion
Valve .................................................................... .
165
Checking of Refrigerant Leaks ..............................166
Checking System for Leaks Using the Fluorescent
Dye Leak Detector ................................................
166
Dye Injection .........................................................166
Electronic Refrigerant Leak Detector ....................167
SERVICE DATA AND SPECIFICATIONS
(SDS) ................................................................
170
Service Data and Specification (SDS) ..................170

PRECAUTIONSATC-7
< SERVICE INFORMATION >
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Rear A/C
CAUTION:
The new and former refrigerant connections use diffe rent O-ring configurations. Do not confuse O-
rings since they are not interchangeable. If a wrong O-ring is installed, refrigerant will leak at or
around the connection.
O-Ring Part Numbers and Specifications
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 motor 6. 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 size E. O-ring size
⇐ Front
NOTE: The O-ring size 8 is the high-side and the O-ring size 16 is the low-side.

ATC-18
< SERVICE INFORMATION >
REFRIGERATION SYSTEM
REAR REFRIGERATION SYSTEM
1. Defroster nozzle 2. LH side demister duct 3. LH ventilator duct
4. RH side demister duct 5. RH ventilator duct 6. Center ventilator duct
7. Front heater and cooling unit assembly 8. Floor duct 9. Clips
10. Heat duct
WJIA0956E

REFRIGERATION SYSTEMATC-19
< SERVICE INFORMATION >
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O P1. Rear floor duct 2. Rear heater and cooling unit assembly 3. Rear lower overhead duct
4. Rear upper overhead duct
LJIA0142E

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-61
< SERVICE INFORMATION >
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Subsequently, HOT/COLD or DEFROST/VENT or FR ESH/RECIRCULATION operation is selected. The new
door position data is returned to the front air control.
Air Mix Door Control Specification
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
WJIA1244E
WJIA0435E
WJIA2309E
WJIA1245E

TROUBLE DIAGNOSISATC-75
< SERVICE INFORMATION >
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• 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 moto r 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 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.
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.
WJIA1354E
WJIA0592E
WJIA2277E

TROUBLE DIAGNOSISATC-109
< SERVICE INFORMATION >
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OK >> GO TO 6.
NG >> Check the air mix door motor circuit. Refer to ATC-59, "
Air Mix Door Motor Circuit" .
6.CHECK AIR DUCTS
Check for disconnected or leaking air ducts.
OK or NG
OK >> GO TO 7.
NG >> 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.
OK or NG
OK >> Hot inlet hose and a warm outlet hose: GO TO 8.
NG >> • Inlet hose cold: GO TO 11. • Both hoses warm: GO TO 9.
8.CHECK ENGINE COOLANT SYSTEM
Check engine control temperature sensor. Refer to EC-205
.
OK or NG
OK >> System OK.
NG >> Repair or replace as necessary. Retest.
9.CHECK HEATER HOSES
Check heater hoses for proper installation.
OK or NG
OK >> System OK.
NG >> 1. Back flush heater core. 2. Drain the water from the system.
3. Refill system with new engine coolant. Refer to CO-9, "
Changing Engine Coolant" .
4. GO TO 10 to retest.
10.CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses.
OK or NG
OK >> System OK.
NG >> Replace heater core. Refer to ATC-135
.
11 .CHECK WATER VALVE
Check the operation of the water valve. Refer to ATC-113, "
Water Valve Circuit".
OK or NG
OK >> System OK.
NG >> Replace water valve.
NoiseINFOID:0000000003533262
SYMPTOM: Noise
INSPECTION FLOW