2005 INFINITI QX4 sensor

ATC-2Revision: October 20052005 QX56 SWITCHES AND THEIR CONTROL FUNCTION ... 31
CAN Communication System Description .............. 32
TROUBLE DIAGNOSIS ............................................ 33
CONSULT-II Function (HVAC) ................................ 33
CONSULT-II BASIC OPERATION ....................... 33
SELF-DIAGNOSIS .............................................. 34
DATA MONITOR .................................................. 34
CONSULT-II Function (BCM) .................................. 36
CONSULT-II BASIC OPERATION ....................... 36
DATA MONITOR .................................................. 37
How to Perform Trouble Diagnosis for Quick and
Accurate Repair ...................................................... 38
WORK FLOW ...................................................... 38
SYMPTOM TABLE .............................................. 38
Component Parts and Harness Connector Location ... 39
ENGINE COMPARTMENT .................................. 39
FRONT PASSENGER COMPARTMENT ............ 40
REAR PASSENGER COMPARTMENT ............... 41
Schematic ............................................................... 42
Wiring Diagram — A/C,A — ................................... 43
Front Air Control Terminals and Reference Value ... 53
PIN CONNECTOR TERMINAL LAYOUT ............ 53
TERMINALS AND REFERENCE VALUE FOR
FRONT AIR CONTROL ....................................... 53
A/C System Self-diagnosis Function ...................... 55
DESCRIPTION .................................................... 55
Operational Check (Front) ...................................... 57
CHECKING MEMORY FUNCTION ..................... 57
CHECKING BLOWER ......................................... 57
CHECKING DISCHARGE AIR ............................ 58
CHECKING RECIRCULATION ............................ 58
CHECKING TEMPERATURE DECREASE ......... 58
CHECKING TEMPERATURE INCREASE .......... 59
CHECK A/C SWITCH .......................................... 59
CHECKING AUTO MODE ................................... 59
Operational Check (Rear) ....................................... 60
CHECKING BLOWER ......................................... 60
CHECKING TEMPERATURE DECREASE ......... 60
CHECKING TEMPERATURE INCREASE .......... 60
Power Supply and Ground Circuit for Front Air Con-
trol ........................................................................... 61
INSPECTION FLOW ........................................... 61
COMPONENT DESCRIPTION ............................ 62
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM ... 62
Mode Door Motor Circuit ........................................ 64
INSPECTION FLOW ........................................... 64
SYSTEM DESCRIPTION .................................... 65
COMPONENT DESCRIPTION ............................ 66
DIAGNOSTIC PROCEDURE FOR MODE
DOOR MOTOR ................................................... 66
Air Mix Door Motor Circuit ...................................... 70
INSPECTION FLOW ........................................... 70
SYSTEM DESCRIPTION .................................... 71
COMPONENT DESCRIPTION ............................ 72
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (DRIVER) ................................... 72
DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER) .......................... 76
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR (REAR) ......................................79
Intake Door Motor Circuit ........................................83
INSPECTION FLOW ............................................83
SYSTEM DESCRIPTION .....................................84
COMPONENT DESCRIPTION ............................85
DIAGNOSTIC PROCEDURE FOR INTAKE
DOOR MOTOR ....................................................85
Defroster Door Motor Circuit ...................................87
SYMPTOM: ..........................................................87
INSPECTION FLOW ............................................87
SYSTEM DESCRIPTION .....................................88
COMPONENT DESCRIPTION ............................88
DIAGNOSTIC PROCEDURE FOR
DEFROSTER DOOR MOTOR .............................89
Front Blower Motor Circuit ......................................93
INSPECTION FLOW ............................................93
SYSTEM DESCRIPTION .....................................94
COMPONENT DESCRIPTION ............................95
DIAGNOSTIC PROCEDURE FOR BLOWER
MOTOR ................................................................95
COMPONENT INSPECTION ............................. 100
Rear Blower Motor Circuit ..................................... 101
INSPECTION FLOW .......................................... 101
SYSTEM DESCRIPTION ................................... 102
DIAGNOSTIC PROCEDURE FOR REAR
BLOWER MOTOR ............................................. 102
COMPONENT INSPECTION .............................110
Rear Air Control Circuit .........................................112
INSPECTION FLOW ..........................................112
SYSTEM DESCRIPTION ...................................113
DIAGNOSTIC PROCEDURE FOR REAR AIR
CONTROL .........................................................113
Magnet Clutch Circuit ............................................115
INSPECTION FLOW ..........................................115
SYSTEM DESCRIPTION ...................................116
DIAGNOSTIC PROCEDURE FOR MAGNET
CLUTCH ............................................................116
Insufficient Cooling ................................................ 121
INSPECTION FLOW .......................................... 121
PERFORMANCE TEST DIAGNOSES .............. 122
PERFORMANCE CHART .................................. 124
TROUBLE DIAGNOSES FOR UNUSUAL PRES-
SURE ................................................................. 125
Insufficient Heating ............................................... 128
INSPECTION FLOW .......................................... 128
Noise ..................................................................... 129
INSPECTION FLOW .......................................... 130
Self-diagnosis ....................................................... 132
INSPECTION FLOW .......................................... 132
Memory Function .................................................. 133
INSPECTION FLOW .......................................... 133
Water Valve Circuit ................................................ 133
COMPONENT DESCRIPTION .......................... 133
DIAGNOSTIC PROCEDURE FOR WATER
VALVE ................................................................ 134
COMPONENT INSPECTION ............................. 136
Ambient Sensor Circuit ......................................... 137
COMPONENT DESCRIPTION .......................... 137
AMBIENT TEMPERATURE INPUT PROCESS . 137

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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

ATC-4Revision: October 20052005 QX56 INSTALLATION ..................................................183
Removal and Installation for High-pressure Flexible
Hose .....................................................................183
REMOVAL .........................................................183
INSTALLATION ..................................................183
Removal and Installation for High-pressure Pipe . 183
REMOVAL .........................................................183
INSTALLATION ..................................................183
Removal and Installation for Low-pressure Pipe ..184
REMOVAL .........................................................184
INSTALLATION ..................................................184
Removal and Installation for Underfloor Rear A/C
Pipes .....................................................................184
REMOVAL .........................................................184
INSTALLATION ..................................................184
Removal and Installation for Rear A/C Pipes .......184
REMOVAL .........................................................184
INSTALLATION ..................................................184
Removal and Installation for Refrigerant Pressure
Sensor ..................................................................185
REMOVAL .........................................................185
INSTALLATION ..................................................185
Removal and Installation for Condenser ...............185
REMOVAL .........................................................185
INSTALLATION ..................................................185
Removal and Installation for Front Evaporator .....186REMOVAL .......................................................... 186
INSTALLATION .................................................. 187
Removal and Installation for Rear Evaporator ...... 187
REMOVAL .......................................................... 188
INSTALLATION .................................................. 188
Removal and Installation for Front Expansion Valve . 188
REMOVAL .......................................................... 188
INSTALLATION .................................................. 188
Removal and Installation for Rear Expansion Valve . 188
REMOVAL .......................................................... 188
INSTALLATION .................................................. 189
Checking for Refrigerant Leaks ............................ 189
Checking System for Leaks Using the Fluorescent
Dye Leak Detector ................................................ 189
Dye Injection ......................................................... 189
Electronic Refrigerant Leak Detector .................... 190
PRECAUTIONS FOR HANDLING LEAK
DETECTOR ....................................................... 190
CHECKING PROCEDURE ................................ 191
SERVICE DATA AND SPECIFICATIONS (SDS) .... 193
Service Data and Specifications (SDS) ................ 193
COMPRESSOR ................................................. 193
LUBRICANT ....................................................... 193
REFRIGERANT ................................................. 193
ENGINE IDLING SPEED ................................... 193
BELT TENSION ................................................. 193

PRECAUTIONS
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A/C Identification LabelEJS003WT
Vehicles with factory installed fluorescent dye have this identification
label on the underside of hood.
Precautions for Refrigerant ConnectionEJS003WU
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.
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SHA8 15 E

PRECAUTIONS
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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
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1. Rear A/C pipes 2. Underfloor rear A/C pipes 3. Underfloor rear heater pipes
⇐Front

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REFRIGERATION SYSTEM
Revision: October 20052005 QX56
REFRIGERATION SYSTEMPFP:KA990
Refrigerant CycleEJS003X1
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 ProtectionEJS003X2
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 de-energizes 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: October 20052005 QX56
AIR CONDITIONER CONTROLPFP:27500
DescriptionEJS003X5
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, also referred to as the front air control, which receives input signals
from the following six sensors:

Ambient sensor

In-vehicle sensor

Intake sensor

Optical sensor (providing one input for driver and one input for passenger side)

PBR (Position Balanced Resistor)

Vehicle speed sensor
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 from rear control
switches located on the front air control, or from the temperature and rear blower settings selected from rear
control switches on the rear air control, when the front air control switches are set to the rear position.
The front air control is used to select:

Outlet air volume

Air temperature/distribution
OperationEJS003X6
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.
BLOWER SPEED CONTROL
Blower speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle tempera-
ture, 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 by the 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
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MAGNET CLUTCH CONTROL
When A/C switch or DEF switch is pressed, front air control inputs compressor ON signal to BCM.
BCM sends compressor ON signal to ECM, via CAN communication line.
ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant pressure sen-
sor signal, throttle angle sensor, etc.). If it judges compressor can be turned ON, it sends compressor ON sig-
nal to IPDM E/R, via CAN communication line.
Upon receipt of compressor ON signal from ECM, IPDM E/R turns air conditioner relay ON to operate com-
pressor.
SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the front air control to quickly locate the cause of symptoms. Refer to
ATC-55, "
A/C System Self-diagnosis Function"
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