2005 INFINITI QX4 clutch

PREPARATION
ATC-17
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AT C
Revision: October 20052005 QX56
Commercial Service ToolsEJS003X0
Tool nameDescription
(J-41810-NI)
Refrigerant identifier equipment (R-
134a)For checking refrigerant purity and
system contamination
Power toolLoosening bolts and nuts
(J-44614)
Clutch disc holding toolClutch disc holding tool
RJIA0197E
PBIC0190E
WHA230

ATC-18
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).

AIR CONDITIONER CONTROL
ATC-25
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AT C
Revision: October 20052005 QX56
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"
WJIA1163E

ATC-38
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
How to Perform Trouble Diagnosis for Quick and Accurate RepairEJS003XF
WORK FLOW
SYMPTOM TABLE
*1AT C - 5 7 , "Operational Check (Front)"
or ATC-60, "
Operational Check
(Rear)" .
SHA9 00 E
Symptom Reference Page
A/C system does not come on. Go to Trouble Diagnosis Procedure for A/C System.AT C - 6 1
A/C system display is malfunctioning. Go to Navigation SystemAV- 6 1
A/C system cannot be controlled. Go to Self-diagnosis Function.AT C - 5 5
Air outlet does not change.
Go to Trouble Diagnosis Procedure for Mode Door Motor.AT C - 6 4
Mode door motor is malfunctioning.
Discharge air temperature does not change.
Go to Trouble Diagnosis Procedure for Air Mix Door Motor.AT C - 7 0
Air mix door motor is malfunctioning.
Intake door does not change.
Go to Trouble Diagnosis Procedure for Intake Door Motor.AT C - 8 3
Intake door motor is malfunctioning.
Defroster door motor is malfunctioning. Go to Trouble Diagnosis Procedure for Defroster Door Motor.AT C - 8 7
Front blower motor operation is malfunction-
ing.Go to Trouble Diagnosis Procedure for Front Blower Motor.AT C - 9 3
Rear blower motor operation is malfunction-
ing.Go to Trouble Diagnosis Procedure for Rear Blower Motor.AT C - 1 0 1
Rear discharge air temperature and/or air
outlet does not change.Go to Trouble Diagnosis Procedure for Rear Air Control circuit.AT C -11 2
Magnet clutch does not engage. Go to Trouble Diagnosis Procedure for Magnet Clutch.AT C -11 5
Insufficient cooling Go to Trouble Diagnosis Procedure for Insufficient Cooling.AT C - 1 2 1
Insufficient heating Go to Trouble Diagnosis Procedure for Insufficient Heating.AT C - 1 2 8
Noise Go to Trouble Diagnosis Procedure for Noise.AT C - 1 2 9
Self-diagnosis cannot be performed. Go to Trouble Diagnosis Procedure for Self-diagnosis.AT C - 1 3 2
Memory function does not operate. Go to Trouble Diagnosis Procedure for Memory Function.AT C - 1 3 3

ATC-56
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SELF-DIAGNOSIS CODE CHART
Code No. Reference page
02 EE changed by calibrationATC-147, "
FRONT AIR CONTROL"
03 Battery voltage out of rangeSC-4, "BATTERY"
12 Air mix door motor (Passenger) circuit failureAT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (PASSENGER)"
20 BCM not responding to A/C requestAT C - 11 6 , "DIAGNOSTIC PROCEDURE FOR MAGNET
CLUTCH"
21 BCM not responding to rear defroster requestGW-77, "REAR WINDOW DEFOGGER"
22 Air mix door motor (Driver) circuit failureAT C - 7 2 , "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (DRIVER)"
30 In-vehicle sensor circuit out of range (low)
ATC-145, "Intake Sensor Circuit"31 In-vehicle sensor circuit out of range (high)
38 Air mix door motor (rear) circuit failureAT C - 7 9 , "
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (REAR)"
40 Ambient sensor circuit short
ATC-137, "Ambient Sensor Circuit"41 Ambient sensor circuit open
44 In-vehicle sensor motor circuit open
ATC-145, "
Intake Sensor Circuit"46 In-vehicle sensor motor circuit short
50 Optical sensor (Driver) circuit open or short
ATC-143, "
Optical Sensor Circuit"52 Optical sensor (Passenger) circuit open or short
56 Intake sensor circuit short
ATC-145, "
Intake Sensor Circuit"57 Intake sensor circuit open
62 Defroster door motor circuit failureAT C - 8 7 , "
Defroster Door Motor Circuit"
80 CAN bus faultLAN-5, "CAN COMMUNICATION"
82 Intake door motor (driver) circuit malfunctionAT C - 8 5 , "DIAGNOSTIC PROCEDURE FOR INTAKE DOOR
MOTOR"
90 Stuck buttonATC-147, "FRONT AIR CONTROL"
92 Mode door motor circuit failureAT C - 6 4 , "Mode Door Motor Circuit"

ATC-58
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
CHECKING DISCHARGE AIR
1. Press MODE switch four times and the DEF switch.
2. Each position indicator should change shape (on display).
3. Confirm that discharge air comes out according to the air distri-
bution table. Refer to ATC-29, "
Discharge Air Flow" .
Mode door position is checked in the next step.
If NG, go to trouble diagnosis procedure for AT C - 6 4 , "
Mode Door
Motor Circuit" .
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or visual
inspection) and intake door position is at fresh when the DEF or D/F
is selected.
CHECKING RECIRCULATION
1. Press recirculation ( ) switch one time. Recirculation indica-
tor should illuminate.
2. Press recirculation ( ) switch one more time. Recirculation
indicator should go off.
3. Listen for intake door position change (blower sound should
change slightly).
If NG, go to trouble diagnosis procedure for ATC-83, "
Intake Door
Motor Circuit" .
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or visual
inspection) and intake door position is at fresh when the DEF or D/F is selected.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature control dial (driver side or passenger side)
counterclockwise until 16°C (60°F) is displayed.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-121, "
Insufficient Cooling" . If
air mix door motor appears to be malfunctioning, go to ATC-72,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(DRIVER)" or AT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER)" .
If OK, continue the check.
WJIA1045E
WJIA0528E
WJIA1046E
WJIA1047E

TROUBLE DIAGNOSIS
ATC-59
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Revision: October 20052005 QX56
CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockwise (driver side or passen-
ger side) until 32°C (90°F) is displayed.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-128, "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to AT C - 7 2 ,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(DRIVER)" or AT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER)" .
If OK, continue with next check.
CHECK A/C SWITCH
1. Press A/C switch when AUTO switch is ON, or in manual mode.
2. A/C switch indicator will turn ON.

Confirm that the compressor clutch engages (sound or visual
inspection).
If NG, go to trouble diagnosis procedure for AT C - 11 5
.
If OK, continue with next check.
CHECKING AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO.

If ambient temperature is warm, and selected temperature is
cool, confirm that the compressor clutch engages (sound or
visual inspection). (Discharge air and blower speed will
depend on ambient, in-vehicle, and set temperatures.)
If NG, go to trouble diagnosis procedure for ATC-61, "
Power Supply
and Ground Circuit for Front Air Control" , then if necessary, trouble
diagnosis procedure for ATC-115, "
Magnet Clutch Circuit" .
If all operational checks are OK (symptom cannot be duplicated), go
to malfunction Simulation Tests in ATC-38, "
How to Perform Trouble
Diagnosis for Quick and Accurate Repair" and perform tests as out-
lined to simulate driving conditions environment. If symptom appears. Refer to AT C - 3 8 , "
How to Perform Trou-
ble Diagnosis for Quick and Accurate Repair" , ATC-38, "SYMPTOM TABLE" and perform applicable trouble
diagnosis procedures.
WJIA1048E
WJIA1049E
WJIA1043E

TROUBLE DIAGNOSIS
ATC-115
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AT C
Revision: October 20052005 QX56
Magnet Clutch CircuitEJS003XV
SYMPTOM: Magnet clutch does not engage.
INSPECTION FLOW
*1ATC-57, "Operational Check (Front)"*2AT C - 5 5 , "A/C System Self-diagnosis
Function"
*3AT C - 5 6 , "SELF-DIAGNOSIS CODE
CHART"
*4ATC-137, "Ambient Sensor Circuit"*5ATC-145, "Intake Sensor Circuit"
WJIA1285E