Ac system INFINITI QX4 2001 Factory Service Manual

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

Overview of Control System=NBHA0015The control system consists of input sensors, switches, the automatic amplifier (microcomputer) and outputs.
The relationship of these components is shown in the diagram below:
RHA856H
Control OperationNBHA0016
RHA452GA
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
DESCRIPTION
Overview of Control System
HA-23

RHA328HA
DISPLAY SCREENNBHA0016S01Displays the operational status of the system.
AUTO SWITCHNBHA0016S02The compressor, intake doors, air mix door, outlet doors, and blower speed are automatically controlled so
that the in-vehicle temperature will reach, and be maintained at the set temperature selected by the operator.
ECON SWITCHNBHA0016S03By pressing the ECON switch, the display should indicate ECON and the compressor always turns OFF. With
the compressor OFF, the system will not remove heat (cool) or de-humidify. The system will maintain the in-
vehicle temperature at the set temperature when the set temperature is above the ambient (outside) tempera-
ture. The system will set the intake doors to the outside air position.
TEMPERATURE SWITCH (POTENTIO TEMPERATURE CONTROL) WITHOUT NAVIGATION
SYSTEM
NBHA0016S04Increases or decreases the set temperature.
OFF SWITCHNBHA0016S05The compressor and blower are OFF, the intake doors are set to the outside air position, and the air outlet
doors are set to the foot (80% foot and 20% defrost) position.
FAN SWITCHNBHA0016S06Manually controls the blower speed. Four speeds are available for manual control (as shown on the display
screen):
low
, medium low, medium high, high
RECIRCULATION (REC) SWITCHNBHA0016S07OFF position: Outside air is drawn into the passenger compartment.
ON position: Interior air is recirculated inside the vehicle.
DEFROSTER (DEF) SWITCHNBHA0016S08Positions the air outlet doors to the defrost position. Also positions the intake doors to the outside air position.
MODE SWITCHNBHA0016S09Controls the air discharge outlets.
TEMPERATURE DIAL (POTENTIO TEMPERATURE CONTROL) WITH NAVIGATION SYSTEMNBHA0016S10Increases or decreases the set temperature.
AMB (AMBIENT) SWITCH (WITH NAVIGATION SYSTEM)NBHA0016S11Shows the ambient (outside) air temperature on the display screen for 5 seconds.
DESCRIPTION
Control Operation (Cont'd)
HA-24

System DescriptionNBHA0110SWITCHES AND THEIR CONTROL FUNCTIONSNBHA0110S01
RHA044GA
Position
or switchMODE SW DEF SW
AUTO
SWECON
SWREC SW Temperature SW
VENT B/L FOOT D/F ON OFF ON OFF
Door18.0ÉC
(65ÉF)Ð32.0ÉC
(85ÉF)
Ventila-
tor doorA BCCC
Ð AUTO AUTOÐÐ
Foot
doorABCCA Ð Ð
Defroster
doorAABCC Ð Ð
Air mix
doorÐ Ð Ð A AUTO B
Intake
doorÐ C A AUTO*1 Ð
*1: Automatically controlled when REC switch is OFF.
DESCRIPTION
System Description
HA-26

PASSENGER COMPARTMENTNBHA0033S02Without Navigation SystemNBHA0033S0201
RHA498G
TROUBLE DIAGNOSES
Component Location (Cont'd)
HA-28

With Navigation SystemNBHA0033S0202
RHA857H
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Component Location (Cont'd)
HA-29

Circuit Diagram (Without Navigation System)NBHA0034
MHA973A
TROUBLE DIAGNOSES
Circuit Diagram (Without Navigation System)
HA-30

Wiring Diagram Ð A/C, A Ð (Without
Navigation System)
NBHA0035
MHA974A
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Wiring Diagram Ð A/C, A Ð (Without Navigation System)
HA-31

MHA975A
TROUBLE DIAGNOSES
Wiring Diagram Ð A/C, A Ð (Without Navigation System) (Cont'd)
HA-32

MHA976A
GI
MA
EM
LC
EC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
Wiring Diagram Ð A/C, A Ð (Without Navigation System) (Cont'd)
HA-33