2004 INFINITI QX56 sensor

ATC-2Revision: August 20072004 QX56 TROUBLE DIAGNOSIS ............................................ 33
CONSULT-II Function (BCM) .................................. 33
CONSULT-II BASIC OPERATION ....................... 33
DATA MONITOR .................................................. 34
How to Perform Trouble Diagnosis for Quick and
Accurate Repair ...................................................... 35
WORK FLOW ...................................................... 35
SYMPTOM TABLE .............................................. 35
Component Parts and Harness Connector Location ... 37
ENGINE COMPARTMENT .................................. 37
FRONT PASSENGER COMPARTMENT ............ 38
REAR PASSENGER COMPARTMENT ............... 39
Schematic ............................................................... 40
Wiring Diagram — A/C,A — ................................... 41
Front Air Control Terminals and Reference Value ... 51
PIN CONNECTOR TERMINAL LAYOUT ............ 51
TERMINALS AND REFERENCE VALUE FOR
FRONT AIR CONTROL ....................................... 51
A/C System Self-diagnosis Function ...................... 53
DESCRIPTION .................................................... 53
Operational Check (Front) ...................................... 56
CHECKING MEMORY FUNCTION ..................... 56
CHECKING BLOWER ......................................... 56
CHECKING DISCHARGE AIR ............................ 57
CHECKING RECIRCULATION ............................ 57
CHECKING TEMPERATURE DECREASE ......... 57
CHECKING TEMPERATURE INCREASE .......... 58
CHECK A/C SWITCH .......................................... 58
CHECKING AUTO MODE ................................... 58
Operational Check (Rear) ....................................... 59
CHECKING BLOWER ......................................... 59
CHECKING TEMPERATURE DECREASE ......... 59
CHECKING TEMPERATURE INCREASE .......... 59
Power Supply and Ground Circuit for Front Air Con-
trol ........................................................................... 60
INSPECTION FLOW ........................................... 60
COMPONENT DESCRIPTION ............................ 61
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM ... 61
Mode Door Motor Circuit ........................................ 63
INSPECTION FLOW ........................................... 63
SYSTEM DESCRIPTION .................................... 64
COMPONENT DESCRIPTION ............................ 65
DIAGNOSTIC PROCEDURE FOR MODE
DOOR MOTOR ................................................... 65
Air Mix Door Motor Circuit ...................................... 67
INSPECTION FLOW ........................................... 67
SYSTEM DESCRIPTION .................................... 68
COMPONENT DESCRIPTION ............................ 69
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (DRIVER) ................................... 69
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER) .......................... 71
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (REAR) ...................................... 73
Intake Door Motor Circuit ........................................ 76
INSPECTION FLOW ........................................... 76
SYSTEM DESCRIPTION .................................... 77
COMPONENT DESCRIPTION ............................ 78
DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR ....................................................78
Defroster Door Motor Circuit ...................................79
SYMPTOM: ..........................................................79
INSPECTION FLOW ............................................79
SYSTEM DESCRIPTION .....................................80
COMPONENT DESCRIPTION ............................80
DIAGNOSTIC PROCEDURE FOR
DEFROSTER DOOR MOTOR .............................81
Front Blower Motor Circuit ......................................83
INSPECTION FLOW ............................................83
SYSTEM DESCRIPTION .....................................84
COMPONENT DESCRIPTION ............................85
DIAGNOSTIC PROCEDURE FOR BLOWER
MOTOR ................................................................85
COMPONENT INSPECTION ...............................89
Rear Blower Motor Circuit .......................................90
INSPECTION FLOW ............................................90
SYSTEM DESCRIPTION .....................................91
DIAGNOSTIC PROCEDURE FOR REAR
BLOWER MOTOR ...............................................91
COMPONENT INSPECTION ...............................99
Rear Air Control Circuit ......................................... 101
INSPECTION FLOW .......................................... 101
SYSTEM DESCRIPTION ................................... 102
DIAGNOSTIC PROCEDURE FOR REAR AIR
CONTROL ......................................................... 102
Magnet Clutch Circuit ............................................ 104
INSPECTION FLOW .......................................... 104
SYSTEM DESCRIPTION ................................... 105
DIAGNOSTIC PROCEDURE FOR MAGNET
CLUTCH ............................................................ 105
Insufficient Cooling ................................................110
INSPECTION FLOW ..........................................110
PERFORMANCE TEST DIAGNOSES .............. 111
PERFORMANCE CHART ..................................113
TROUBLE DIAGNOSES FOR UNUSUAL PRES-
SURE .................................................................114
Insufficient Heating ...............................................117
INSPECTION FLOW ..........................................117
Noise .....................................................................118
INSPECTION FLOW ..........................................118
Self-diagnosis ....................................................... 120
INSPECTION FLOW .......................................... 120
Memory Function .................................................. 121
INSPECTION FLOW .......................................... 121
Water Valve Circuit ................................................ 121
COMPONENT DESCRIPTION .......................... 121
DIAGNOSTIC PROCEDURE FOR WATER
VALVE ................................................................ 122
COMPONENT INSPECTION ............................. 124
Ambient Sensor Circuit ......................................... 125
COMPONENT DESCRIPTION .......................... 125
AMBIENT TEMPERATURE INPUT PROCESS . 125
DIAGNOSTIC PROCEDURE FOR AMBIENT
SENSOR ............................................................ 125
COMPONENT INSPECTION ............................. 127
In-vehicle Sensor Circuit ....................................... 128
COMPONENT DESCRIPTION .......................... 128
DIAGNOSTIC PROCEDURE FOR IN-VEHICLE

ATC-3
C
D
E
F
G
H
I
K
L
MA
B
AT C
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
ATC-7
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
A/C Identification LabelEJS002BK
Vehicles with factory installed fluorescent dye have this identification
label on the underside of hood.
Precautions for Refrigerant ConnectionEJS002BL
A new type refrigerant connection has been introduced to all refrigerant lines except the following locations.

Expansion valve to cooling unit

Evaporator pipes to evaporator (inside cooling unit)

Refrigerant pressure sensor
FEATURES OF NEW TYPE REFRIGERANT CONNECTION

The O-ring has been relocated. It has also been provided with a groove for proper installation. This
reduces the possibility of the O-ring being caught in, or damaged by, the mating part. The sealing direction
of the O-ring is now set vertically in relation to the contacting surface of the mating part to improve sealing
characteristics.

The reaction force of the O-ring will not occur in the direction that causes the joint to pull out, thereby facil-
itating piping connections.
WJIA0672E
SHA8 15 E

PRECAUTIONS
ATC-9
C
D
E
F
G
H
I
K
L
MA
B
AT C
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.

ATC-18
REFRIGERATION SYSTEM
Revision: August 20072004 QX56
REFRIGERATION SYSTEMPFP:KA990
Refrigerant CycleEJS002BS
REFRIGERANT FLOW
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser with liquid tank,
through the front and rear evaporators, and back to the compressor. The refrigerant evaporation through the
evaporator coils are controlled by front and rear externally equalized expansion valves, located inside the front
and rear evaporator cases.
Refrigerant System ProtectionEJS002BT
REFRIGERANT PRESSURE SENSOR
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sen-
sor, located on the condenser. If the system pressure rises above or falls below the specifications, the refriger-
ant pressure sensor detects the pressure inside the refrigerant line and sends a voltage signal to the ECM.
The ECM deenergizes the A/C relay to disengage the magnetic compressor clutch when pressure on the high
pressure side detected by refrigerant pressure sensor is over about 2,746 kPa (28 kg/cm
2 , 398 psi), or below
about 120 kPa (1.22 kg/cm
2 , 17.4 psi).

ATC-24
AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
AIR CONDITIONER CONTROLPFP:27500
DescriptionEJS002BW
The front air control provides automatic regulation of the vehicle's interior temperature. The system is based
on the driver's and passenger's selected "set temperature", regardless of the outside temperature changes.
This is done by utilizing a microcomputer that is part of the front air control, which receives input signals from
the following five sensors:

Ambient sensor

In-vehicle sensor

Intake sensor

Optical sensor (one sensor for driver and passenger side)

PBR (position balanced resistor)
The front air control uses these signals (including the set temperature) to automatically control:

Outlet air volume

Air temperature

Air distribution
The front air control also provides separate regulation of the vehicle's interior temperature for the rear passen-
ger area. The system is based on the temperature and rear blower settings selected on the front air control
rear fan switch (front) and rear temperature/mode dial (front), or from the rear fan switch (rear) and rear tem-
perature/mode dial (rear) on the rear air control, when the rear fan switch (front) is set to the rear (R) position.
The front air control or rear air control is used to select:

Outlet air volume

Air temperature/mode distribution
OperationEJS002BX
AIR MIX DOORS CONTROL
The air mix doors are automatically controlled so that in-vehicle temperature is maintained at a predetermined
value by the temperature setting, ambient temperature, in-vehicle temperature and amount of sunload.
FAN SPEED CONTROL
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle tem-
perature, intake temperature, amount of sunload and air mix door position.
When AUTO switch is pressed, the blower motor starts to gradually increase air flow volume (if required).
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.
INTAKE DOOR CONTROL
The intake door is automatically controlled by the temperature setting, ambient temperature, in-vehicle tem-
perature, intake temperature, amount of sunload and ON-OFF operation of the compressor.
MODE DOOR CONTROL
The mode door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temper-
ature, intake temperature and amount of sunload.
DEFROSTER DOOR CONTROL
The defroster door is controlled by turning the defroster dial to front defroster.

AIR CONDITIONER CONTROL
ATC-25
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
MAGNET CLUTCH CONTROL
When the A/C or DEF switch is activated, the front air control outputs a compressor ON signal to the BCM.
Upon receiving this input, the BCM sends a compressor ON signal to the ECM via CAN communication lines.
The ECM then judges whether the compressor can be turned ON, based on each sensor status (refrigerant
pressure sensor signal, throttle angle sensor, etc.). If it determines the compressor can be turned ON, a com-
pressor ON signal is sent to the IPDM E/R via CAN communication lines.
Upon receipt of a compressor ON signal, the IPDM E/R turns ON the A/C relay which engages the magnet
clutch and operates the A/C compressor.
SELF-DIAGNOSTIC SYSTEM
A self-diagnostic system is built into the front air control to quickly locate the cause of symptoms. Refer to
ATC-53, "
A/C System Self-diagnosis Function"
WJIA0751E