2004 INFINITI QX56 heater

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Revision: August 20072004 QX56 SENSOR ........................................................... 129
COMPONENT INSPECTION ............................ 131
Optical Sensor Circuit .......................................... 131
COMPONENT DESCRIPTION ......................... 131
OPTICAL INPUT PROCESS ............................ 131
DIAGNOSTIC PROCEDURE FOR OPTICAL
SENSOR ........................................................... 132
Intake Sensor Circuit ............................................ 133
COMPONENT DESCRIPTION ......................... 133
DIAGNOSTIC PROCEDURE FOR INTAKE SEN-
SOR .................................................................. 133
COMPONENT INSPECTION ............................ 134
CONTROL UNIT ..................................................... 135
Removal and Installation ...................................... 135
FRONT AIR CONTROL .................................... 135
REAR AIR CONTROL ....................................... 135
AMBIENT SENSOR ................................................ 136
Removal and Installation ...................................... 136
REMOVAL ......................................................... 136
INSTALLATION ................................................. 136
IN-VEHICLE SENSOR ............................................ 137
Removal and Installation ...................................... 137
REMOVAL ......................................................... 137
INSTALLATION ................................................. 137
OPTICAL SENSOR ................................................ 138
Removal and Installation ...................................... 138
INTAKE SENSOR ................................................... 139
Removal and Installation ...................................... 139
REMOVAL ......................................................... 139
INSTALLATION ................................................. 139
BLOWER MOTOR .................................................. 140
Components ......................................................... 140
Removal and Installation ...................................... 140
FRONT BLOWER MOTOR ............................... 140
REAR BLOWER MOTOR ................................. 141
IN-CABIN MICROFILTER ....................................... 142
Removal and Installation ...................................... 142
FUNCTION ........................................................ 142
REPLACEMENT TIMING .................................. 142
REPLACEMENT PROCEDURE ....................... 142
HEATER & COOLING UNIT ASSEMBLY .............. 144
Components ......................................................... 144
Removal and Installation ...................................... 145
FRONT HEATER AND COOLING UNIT ASSEM-
BLY .................................................................... 145
REAR HEATER AND COOLING UNIT ASSEM-
BLY .................................................................... 146
HEATER CORE ...................................................... 147
Components ......................................................... 147
Removal and Installation ...................................... 148
FRONT HEATER CORE ................................... 148
REAR HEATER CORE ..................................... 149
DEFROSTER DOOR MOTOR ................................ 150
Removal and Installation ...................................... 150
REMOVAL ......................................................... 150
INSTALLATION ................................................. 150INTAKE DOOR MOTOR .........................................151
Removal and Installation ......................................151
REMOVAL .........................................................151
INSTALLATION .................................................151
MODE DOOR MOTOR ............................................152
Removal and Installation ......................................152
REMOVAL .........................................................152
INSTALLATION .................................................152
AIR MIX DOOR MOTOR .........................................153
Components .........................................................153
Removal and Installation ......................................153
FRONT AIR MIX DOOR MOTOR (DRIVER) .....153
FRONT AIR MIX DOOR MOTOR (PASSENGER) .154
REAR AIR MIX DOOR MOTOR ........................154
VARIABLE BLOWER CONTROL ...........................155
Removal and Installation ......................................155
REMOVAL .........................................................155
INSTALLATION .................................................155
REAR BLOWER MOTOR RESISTOR ....................156
Removal and Installation ......................................156
REMOVAL .........................................................156
INSTALLATION .................................................156
DUCTS AND GRILLES ...........................................157
Components .........................................................157
Removal and Installation ......................................160
CENTER CONSOLE HEAT DUCT AND REAR
FINISHER ASSEMBLY GRILLE ........................160
DEFROSTER NOZZLE .....................................160
RH AND LH SIDE DEMISTER DUCT ...............160
RH AND LH VENTILATOR DUCT .....................160
CENTER VENTILATOR DUCT .........................160
FLOOR DUCT ...................................................160
REAR OVERHEAD DUCTS ..............................160
REAR FLOOR DUCT ........................................161
GRILLES ...........................................................161
REFRIGERANT LINES ...........................................162
HFC-134a (R-134a) Service Procedure ...............162
SETTING OF SERVICE TOOLS AND EQUIP-
MENT ................................................................162
Components .........................................................164
Removal and Installation for Compressor ............166
REMOVAL .........................................................166
INSTALLATION .................................................167
Removal and Installation for Compressor Clutch . 167
REMOVAL .........................................................167
INSPECTION ....................................................168
INSTALLATION .................................................168
BREAK-IN OPERATION ....................................170
Removal and Installation for Low-pressure Flexible
Hose .....................................................................170
REMOVAL .........................................................170
INSTALLATION .................................................170
Removal and Installation for High-pressure Flexible
Hose .....................................................................170
REMOVAL .........................................................170
INSTALLATION .................................................170
Removal and Installation for High-pressure Pipe . 170
REMOVAL .........................................................170
INSTALLATION .................................................171

ATC-4Revision: August 20072004 QX56 Removal and Installation for Low-pressure Pipe ..171
REMOVAL .........................................................171
INSTALLATION ..................................................171
Removal and Installation for Rear High- and Low-
pressure A/C and Heater Core Pipes ...................171
REMOVAL .........................................................171
INSTALLATION ..................................................172
Removal and Installation for Underfloor Rear High-
and Low-pressure A/C and Heater Core Pipes ....172
REMOVAL .........................................................172
INSTALLATION ..................................................173
Removal and Installation for Refrigerant Pressure
Sensor ..................................................................173
REMOVAL .........................................................173
INSTALLATION ..................................................173
Removal and Installation for Condenser ...............173
REMOVAL .........................................................173
INSTALLATION ..................................................174
Removal and Installation for Front Evaporator .....175
REMOVAL .........................................................175
INSTALLATION ..................................................176
Removal and Installation for Rear Evaporator ......176
REMOVAL .........................................................177INSTALLATION .................................................. 177
Removal and Installation for Front Expansion Valve . 177
REMOVAL .......................................................... 177
INSTALLATION .................................................. 177
Removal and Installation for Rear Expansion Valve . 177
REMOVAL .......................................................... 177
INSTALLATION .................................................. 178
Checking for Refrigerant Leaks ............................ 178
Checking System for Leaks Using the Fluorescent
Dye Leak Detector ................................................ 178
Dye Injection ......................................................... 178
Electronic Refrigerant Leak Detector .................... 179
PRECAUTIONS FOR HANDLING LEAK
DETECTOR ....................................................... 179
CHECKING PROCEDURE ................................ 180
SERVICE DATA AND SPECIFICATIONS (SDS) .... 182
Service Data and Specifications (SDS) ................ 182
COMPRESSOR ................................................. 182
LUBRICANT ....................................................... 182
REFRIGERANT ................................................. 182
ENGINE IDLING SPEED ................................... 182
BELT TENSION ................................................. 182

PRECAUTIONS
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Revision: August 20072004 QX56
Rear A/C
1. High-pressure service valve 2. Grommet 3. 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 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.

REFRIGERATION SYSTEM
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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
1. Rear floor duct 2. Rear heater and cooling unit assembly 3. Rear lower overhead duct
4. Rear upper overhead duct
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TROUBLE DIAGNOSIS
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Revision: August 20072004 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 RESULT FROM FRONT AIR CONTROL SELF-DIAGNOSIS
Self-diagnosis code 92 is present. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2. CHECK POWER SUPPLY AND GROUND CIRCUITS FOR MODE DOOR MOTOR
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49 and mode door
motor connector M142.
3. Check continuity between front air control harness connector
M49 terminal 5 (BR/W) and mode door motor connector M142
terminal 5 (BR/W) and between front air control harness con-
nector M49 terminal 6 (P/L) and mode door motor connector
M142 terminal 6 (P/L).
OK or NG
OK >> Replace mode door motor. Refer to ATC-152, "Removal and Installation" .
NG >> Repair or replace harness as necessary.
3. CHECK PBR REFERENCE SIGNAL VOLTAGE
1. Disconnect mode door motor connector M142.
2. Turn ignition switch ON.
3. Check voltage between mode door motor harness connector
M142 terminal 3 (Y) and ground.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
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5 - 5 : Continuity should exist.
6 - 6 : Continuity should exist.
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3 - Ground : Approx. 5V
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TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
COMPONENT DESCRIPTION
Air Mix Door Motors
The driver and front passenger air mix door motors are attached to
the front heater & cooling unit. 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 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 front air control
by the PBR built into the air mix door motors.
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR (DRIVER)
1. CHECK RESULT FROM FRONT AIR CONTROL SELF-DIAGNOSIS
Self-diagnosis code 22 is present. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
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ATC-80
TROUBLE DIAGNOSIS
Revision: August 20072004 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 rotated counterclockwise, 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. 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 acti-
vates the defroster door.
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TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
Blower Speed Compensation - Sunload
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The speed will vary depending on the sunload. During conditions of low or no sunload, the blower
operates at low speed. During high sunload conditions, the front air control causes the blower speed to
increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the front heater and cooling
unit. The variable blower control receives a gate voltage from the
front air control to steplessly maintain the blower motor voltage in the
0 to 5 volt range (approx.).
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning under starting
blower speed control.
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