2001 INFINITI QX4 Engine control

HEATER &
AIR CONDITIONER
SECTION
HA
CONTENTS
PRECAUTIONS...............................................................2
Supplemental Restraint System (SRS)²AIR
BAG²and²SEAT BELT PRE-TENSIONER²...............2
Precautions for Working with HFC-134a (R-134a) .....2
General Refrigerant Precautions .................................3
Precautions for Leak Detection Dye............................3
Identification .................................................................4
Precautions for Refrigerant Connection ......................4
Precautions for Servicing Compressor ........................6
Precautions for Service Equipment .............................7
Wiring Diagrams and Trouble Diagnoses....................9
PREPARATION.............................................................10
Special Service Tools ................................................10
HFC-134a (R-134a) Service Tools and
Equipment .................................................................. 11
DESCRIPTION...............................................................14
Refrigeration System .................................................14
V-6 Variable Displacement Compressor....................15
Component Layout ....................................................19
Introduction ................................................................20
Features .....................................................................20
Overview of Control System ......................................23
Control Operation ......................................................23
Discharge Air Flow.....................................................25
System Description ....................................................26
TROUBLE DIAGNOSES................................................27
Component Location..................................................27
Circuit Diagram (Without Navigation System) ...........30
Wiring Diagram - A/C, A - (Without Navigation
System) ......................................................................31
Circuit Diagram (With Navigation System) ................35
Wiring Diagram - A/C, A - (With Navigation
System) ......................................................................36
Auto Amp. Terminals and Reference Value...............40
Self-diagnosis ............................................................44
How to Perform Trouble Diagnoses for Quick
and Accurate Repair ..................................................65Operational Check .....................................................66
A/C System ................................................................71
Mode Door Motor.......................................................75
Air Mix Door Motor ....................................................82
Intake Door Motor ......................................................87
Blower Motor..............................................................95
Magnet Clutch..........................................................104
Insufficient Cooling .................................................. 112
Insufficient Heating ..................................................121
Noise ........................................................................123
Self-diagnosis ..........................................................124
Memory Function .....................................................126
ECON (ECONOMY) Mode ......................................128
Ambient Sensor Circuit ............................................129
In-vehicle Sensor Circuit..........................................132
Sunload Sensor Circuit ............................................135
Intake Sensor Circuit ...............................................139
Air Mix Door Motor PBR Circuit ..............................141
Multiplex Communication Circuit .............................142
SERVICE PROCEDURE..............................................144
HFC-134a (R-134a) Service Procedure ..................144
Maintenance of Lubricant Quantity in
Compressor .............................................................146
Compressor .............................................................149
Compressor Clutch ..................................................150
Refrigerant Lines .....................................................154
Belt ...........................................................................159
Ventilation Air Filter ..................................................159
SERVICE DATA AND SPECIFICATIONS (SDS).......160
Compressor .............................................................160
Lubricant ..................................................................160
Refrigerant ...............................................................160
Engine Idling Speed (When A/C is ON) ..................160
Belt Tension .............................................................160
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V-6 Variable Displacement Compressor
GENERAL INFORMATION=NBHA00861. The V-6 variable compressor differs from previous units. The vent temperatures of the V-6 variable com-
press do not drop too far below 5ÉC (41ÉF) when:
Ievaporator intake air temperature is less than 20ÉC (68ÉF)
Iengine is running at speeds less than 1,500 rpm.
This is because the V-6 compressor provides a means of ªcapacityº control.
2. The V-6 variable compressor provides refrigerant control under varying conditions. During cold winters, it
may not produce high refrigerant pressure discharge (compared to previous units) when used with air
conditioning systems.
3. A ªclankingº sound may occasionally be heard during refrigerant charge. The sound indicates that the tilt
angle of the swash plate has changed and is not a problem.
4. For air conditioning systems with the V-6 compressor, the clutch remains engaged unless: the system main
switch, fan switch or ignition switch is turned OFF. When ambient (outside) temperatures are low or when
the amount of refrigerant is insufficient, the clutch is disengaged to protect the compressor.
5. A constant range of suction pressure is maintained when engine speed is greater than a certain value. It
normally ranges from 147 to 177 kPa (1.5 to 1.8 kg/cm
2, 21 to 26 psi) under varying conditions.
In previous compressors, however, suction pressure was reduced with increases in engine speed.
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DESCRIPTION
V-6 Variable Displacement Compressor
HA-15

Fan Speed ControlNBHA0014S0804Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle
temperature, intake temperature, amount of sunload and air mix door position.
With FAN switch set to ªAUTOº, the blower motor starts to gradually increase air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.
Intake Door ControlNBHA0014S0805The intake doors are automatically controlled by: The temperature setting, ambient temperature, in-vehicle
temperature, intake temperature, amount of sunload and ON-OFF operation of the compressor.
Outlet Door ControlNBHA0014S0806The outlet door is automatically controlled by: The temperature setting, ambient temperature, in-vehicle
temperature, intake temperature and amount of sunload.
Magnet Clutch ControlNBHA0014S0807The ECM controls compressor operation using input signals from the throttle position sensor and auto ampli-
fier.
Self-diagnostic SystemNBHA0014S0808The self-diagnostic system is built into the auto amplifier (LCU) to quickly locate the cause of problems.
DESCRIPTION
Features (Cont'd)
HA-22

TERMINAL
NO.ITEM CONDITIONVoltage
V
13 Thermal transmitter
Engine coolant
temperatureApproximately 30ÉC (86ÉF) Approximately 9.4
Approximately 55ÉC (131ÉF) Approximately 6.5
Approximately 100ÉC
(212ÉF)Approximately 2.4
14 Ground (for Canada) Ð Approximately 0
16 A/C LAN signal Ð Approximately 5.5
18 Intake door position switch Intake door position20% FRE or RECIRCULA-
TIONApproximately 0
FRESH Approximately 4.6
19 Intake door position switch Intake door positionRECIRCULATION or
FRESHApproximately 0
20% FRE Approximately 4.6
21Power supply for mode door
motor and air mix door motorÐ Approximately 12
22 Compressor ON signal
CompressorON Approximately 0
OFF Approximately 4.6
24 Power supply for illumination
Lighting switchOFF Approximately 0
1st Approximately 12
25 Illumination ground Ð Approximately 0
26 Power supply for BAT
Ð BATTERY VOLTAGE
27 Power supply for IGN
Ð Approximately 12
28Power supply for intake door
motorIntake door positionFRESH Approximately 12
RECIRC Approximately 0
32 Ground Ð Approximately 0
33 Power source for A/C Ignition voltage feed back Approximately 12
34 Blower motor feed back Fan speed: Low Approximately7-10
35Fan control AMP. control sig-
nalFan speedLow, Middle low or Middle
highApproximately 2.5 -
3.0
High Approximately9-10
36Power supply for intake door
motorIntake door positionFRESH Approximately 0
RECIRC Approximately 12
With Navigation SystemNBHA0036S0202
TERMINAL
NO.ITEM CONDITIONVoltage
V
1 Intake sensor Ð Ð
2 Ambient sensor Ð Ð
3 In-vehicle sensor Ð Ð
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TROUBLE DIAGNOSES
Auto Amp. Terminals and Reference Value (Cont'd)
HA-41

Self-diagnosis=NBHA0021INTRODUCTION AND GENERAL DESCRIPTIONNBHA0021S01The self-diagnostic system diagnoses sensors, door motors, blower motor, etc. by system line. Refer to appli-
cable sections (items) for details. Shifting from normal control to the self-diagnostic system is accomplished
by starting the engine (turning the ignition switch from ªOFFº to ªONº) and pressing ª
º switch for at least
5 seconds. The ª
º switch must be pressed within 10 seconds after starting the engine (ignition switch is
turned ªONº). This system will be canceled by either pressing
(AUTO) switch or turning the ignition switch
ªOFFº. Shifting from one step to another is accomplished by means of pushing
(HOT) or(COLD) switch,
as required.
Additionally shifting from STEP 5 to AUXILIARY MECHANISM is accomplished by means of pushing
(fan)
UP switch.
Without Navigation SystemNBHA0021S0101
RHA453GA
TROUBLE DIAGNOSES
Self-diagnosis
HA-44

INTRODUCTION AND GENERAL DESCRIPTIONNBHA0021S04The self-diagnostic system diagnoses sensors, door motors, blower motor, etc. by system line. Refer to appli-
cable sections (items) for details. Shifting from normal control to the self-diagnostic system is accomplished
by starting the engine (turning the ignition switch from ªOFFº to ªONº) and pressing ª
º switch for at least
5 seconds. The ª
º switch must be pressed within 10 seconds after starting the engine (ignition switch is
turned ªONº). This system will be canceled by either pressing
(AUTO) switch or turning the ignition switch
ªOFFº. Shifting from one step to another is accomplished by means of turning temperature dial, as required.
Additionally shifting from STEP 5 to AUXILIARY MECHANISM is accomplished by means of pushing
(fan)
UP switch.
With Navigation SystemNBHA0021S0401
RHA859H
TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
HA-54

STEP-BY-STEP PROCEDURENBHA0021S05With Navigation SystemNBHA0021S0501
1 SET IN SELF-DIAGNOSTIC MODE
1. Turn ignition switch ON.
2. Set in self-diagnostic mode as follows. Within 10 seconds after starting engine (ignition switch is turned ªONº.), press
switch for at least 5 seconds.
©GO TO 2.
2 STEP 1 - ALL LEDs AND DISPLAY SCREEN ARE CHECKED
When switch's LED and display are functioning properly in STEP-1, LED and display will come on.
RHA860H
OK or NG
OK©GO TO 3.
NG©Malfunctioning
switch, LED or fluorescent display tube.
Go to ªMain Power Supply and Ground Circuit Checkº, HA-72.
3 VERIFY ADVANCE TO SELF-DIAGNOSIS STEP 2
1. Turn temperature dial clockwise.
2. Does advance to self-diagnosis STEP 2?
YesorNo
Ye s©GO TO 4.
No©Malfunctioning temperature dial.
Check Display & NAVI control unit.
4 VERIFY RETURN TO SELF-DIAGNOSIS STEP 1
1. Turn temperature dial counterclockwise.
2. Does return to self-diagnosis STEP 1?
YesorNo
Ye s©GO TO 5.
No©Malfunctioning temperature dial.
Check Display & NAVI control unit.
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TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
HA-55

SYSTEM DESCRIPTION=NBHA0062Component partsNBHA0062S01Fan speed control system components are:
1) Auto amp.
2) Fan control amp.
3) A/C LAN system (PBR built-in mode door motor and air mix door motor)
4) In-vehicle sensor
5) Ambient sensor
6) Sunload sensor
7) Intake sensor
System OperationNBHA0062S02
SHA006FF
Automatic ModeNBHA0062S03In the automatic mode, the blower motor speed is calculated by the automatic amplifier based on inputs from
the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor. The blower motor applied
voltage ranges from approximately 5 volts (lowest speed) to 12 volts (highest speed).
The control blower speed (in the range of 5 to 12V), the automatic amplifier supplies a gate voltage to the fan
control amplifier. Based on this voltage, the fan control amplifier controls the voltage supplied to the blower
motor.
Starting Fan Speed ControlNBHA0062S04Start Up From ªCOLD SOAKº Condition (Automatic mode)NBHA0062S0401In a cold start up condition where the engine coolant temperature is below 50ÉC (122ÉF), the blower will not
operate for a short period of time (up to 126 seconds). The exact start delay time varies depending on the
ambient and engine coolant temperature.
In the most extreme case (very low ambient) the blower starting delay will be 126 seconds as described above.
After this delay, the blower will operate at low speed until the engine coolant temperature rises above 55ÉC
(131ÉF), at which time the blower speed will increase to the objective speed.
Start Up From Normal or ªHOT SOAKº Condition (Automatic mode)
NBHA0062S0402The blower will begin operation momentarily after the AUTO button is pushed. The blower speed will gradu-
ally rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
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TROUBLE DIAGNOSES
Blower Motor (Cont'd)
HA-97