2005 INFINITI QX4 heater

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Revision: October 20052005 QX56 DIAGNOSTIC PROCEDURE FOR AMBIENT
SENSOR ........................................................... 137
COMPONENT INSPECTION ............................ 139
In-vehicle Sensor Circuit ...................................... 140
COMPONENT DESCRIPTION ......................... 140
DIAGNOSTIC PROCEDURE FOR IN-VEHICLE
SENSOR ........................................................... 141
COMPONENT INSPECTION ............................ 143
Optical Sensor Circuit .......................................... 143
COMPONENT DESCRIPTION ......................... 143
OPTICAL INPUT PROCESS ............................ 143
DIAGNOSTIC PROCEDURE FOR OPTICAL
SENSOR ........................................................... 144
Intake Sensor Circuit ............................................ 145
COMPONENT DESCRIPTION ......................... 145
DIAGNOSTIC PROCEDURE FOR INTAKE SEN-
SOR .................................................................. 145
COMPONENT INSPECTION ............................ 146
CONTROL UNIT ..................................................... 147
Removal and Installation ...................................... 147
FRONT AIR CONTROL .................................... 147
REAR AIR CONTROL ....................................... 147
AMBIENT SENSOR ................................................ 148
Removal and Installation ...................................... 148
REMOVAL ......................................................... 148
INSTALLATION ................................................. 148
IN-VEHICLE SENSOR ............................................ 149
Removal and Installation ...................................... 149
REMOVAL ......................................................... 149
INSTALLATION ................................................. 149
OPTICAL SENSOR ................................................ 150
Removal and Installation ...................................... 150
INTAKE SENSOR ................................................... 151
Removal and Installation ...................................... 151
REMOVAL ......................................................... 151
INSTALLATION ................................................. 151
BLOWER MOTOR .................................................. 152
Components ......................................................... 152
Removal and Installation ...................................... 152
FRONT BLOWER MOTOR ............................... 152
REAR BLOWER MOTOR ................................. 153
IN-CABIN MICROFILTER ....................................... 154
Removal and Installation ...................................... 154
FUNCTION ........................................................ 154
REPLACEMENT TIMING .................................. 154
REPLACEMENT PROCEDURE ....................... 154
HEATER & COOLING UNIT ASSEMBLY .............. 156
Components ......................................................... 156
Removal and Installation ...................................... 157
FRONT HEATER AND COOLING UNIT ASSEM-
BLY .................................................................... 157
REAR HEATER AND COOLING UNIT ASSEM-
BLY .................................................................... 158
Removal and Installation for Rear Heater Core
Pipes .................................................................... 158
REMOVAL ......................................................... 158
INSTALLATION ................................................. 159
HEATER CORE ...................................................... 160Components .........................................................160
Removal and Installation ......................................161
FRONT HEATER CORE ...................................161
REAR HEATER CORE ......................................162
DEFROSTER DOOR MOTOR ................................163
Removal and Installation ......................................163
REMOVAL .........................................................163
INSTALLATION .................................................163
INTAKE DOOR MOTOR .........................................164
Removal and Installation ......................................164
REMOVAL .........................................................164
INSTALLATION .................................................164
MODE DOOR MOTOR ............................................165
Removal and Installation ......................................165
REMOVAL .........................................................165
INSTALLATION .................................................165
AIR MIX DOOR MOTOR .........................................166
Components .........................................................166
Removal and Installation ......................................166
FRONT AIR MIX DOOR MOTOR (DRIVER) .....166
FRONT AIR MIX DOOR MOTOR (PASSENGER) .167
REAR AIR MIX DOOR MOTOR ........................167
VARIABLE BLOWER CONTROL ...........................168
Removal and Installation ......................................168
REMOVAL .........................................................168
INSTALLATION .................................................168
REAR BLOWER MOTOR RESISTOR ....................169
Removal and Installation ......................................169
REMOVAL .........................................................169
INSTALLATION .................................................169
DUCTS AND GRILLES ...........................................170
Components .........................................................170
Removal and Installation ......................................173
CENTER CONSOLE HEAT DUCT AND REAR
FINISHER ASSEMBLY GRILLE ........................173
DEFROSTER NOZZLE .....................................173
RH AND LH SIDE DEMISTER DUCT ...............173
RH AND LH VENTILATOR DUCT .....................173
CENTER VENTILATOR DUCT .........................173
FLOOR DUCT ...................................................173
REAR OVERHEAD DUCTS ..............................173
REAR FLOOR DUCT ........................................174
GRILLES ...........................................................174
REFRIGERANT LINES ...........................................175
HFC-134a (R-134a) Service Procedure ...............175
SETTING OF SERVICE TOOLS AND EQUIP-
MENT ................................................................175
Components .........................................................177
Removal and Installation for Compressor ............179
REMOVAL .........................................................179
INSTALLATION .................................................180
Removal and Installation for Compressor Clutch . 180
REMOVAL .........................................................180
INSPECTION ....................................................181
INSTALLATION .................................................181
BREAK-IN OPERATION ....................................183
Removal and Installation for Low-pressure Flexible
Hose .....................................................................183
REMOVAL .........................................................183

PRECAUTIONS
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Revision: October 20052005 QX56
Rear A/C
CAUTION:
The new and former refrigerant connections use different 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.
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
WJIA2001E
1. Rear A/C pipes 2. Underfloor rear A/C pipes 3. Underfloor rear heater pipes
⇐Front

REFRIGERATION SYSTEM
ATC-21
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Revision: October 20052005 QX56
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
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: October 20052005 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-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
WJIA0587E
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M496 5Press
mode
switchBattery
voltage
WJIA1727E
5 - Ground : Continuity should not exist.
6 - Ground : Continuity should not exist.
WJIA1734E

ATC-72
TROUBLE DIAGNOSIS
Revision: October 20052005 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 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.
WJIA1876E
WJIA1877E
WJIA1245E
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M493 4Rotate temp
control dialBattery
voltage
WJIA1735E

ATC-88
TROUBLE DIAGNOSIS
Revision: October 20052005 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. 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.
WJIA1354E
WJIA0592E

TROUBLE DIAGNOSIS
ATC-133
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Revision: October 20052005 QX56
Memory FunctionEJS003Y0
SYMPTOM: Memory function does not operate.
INSPECTION FLOW
Water Valve CircuitEJS003Y1
COMPONENT DESCRIPTION
Water Valve
The water valve cuts the flow of engine coolant to the front and rear
heater cores to allow for maximum cooling during A/C operation. It is
controlled by the front air control through the water valve relay.
*1ATC-61, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 7 , "Operational Check (Front)"*3AT C - 5 5 , "A/C System Self-diagnosis
Function"
*4ATC-56, "SELF-DIAGNOSIS CODE
CHART"
WJIA1287E
WJIA1015E

TROUBLE DIAGNOSIS
ATC-145
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Revision: October 20052005 QX56
Intake Sensor CircuitEJS003Y5
COMPONENT DESCRIPTION
Intake Sensor
The intake sensor is located on the heater & cooling unit. It converts
temperature of air after it passes through the evaporator into a value
which is then input to the front air control.
DIAGNOSTIC PROCEDURE FOR INTAKE SENSOR
SYMPTOM: Intake sensor circuit is open or shorted. Using the CON-
SULT-II, DTC B2581 or B2582 is displayed. Without a CONSULT-II,
code 56 or 57 is indicated on front air control as a result of conduct-
ing the front air control 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 (L/B) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
2. CHECK CIRCUIT CONTINUITY BETWEEN INTAKE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between intake sensor harness connector
M146 terminal 1 (V/R) and front air control harness connector
M49 terminal 21 (V/R).
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
WJIA0571E
WJIA0464E
2 - Ground : Approx. 5V
WJIA1375E
1 - 21 : Continuity should exist.
WJIA1376E