Infiniti QX4 (R50). Manual - part 456

Fan Speed Control

NBHA0014S0804

Blower 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 “AUTO”, 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 Control

NBHA0014S0805

The 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 Control

NBHA0014S0806

The outlet door is automatically controlled by: The temperature setting, ambient temperature, in-vehicle
temperature, intake temperature and amount of sunload.

Magnet Clutch Control

NBHA0014S0807

The ECM controls compressor operation using input signals from the throttle position sensor and auto ampli-
fier.

Self-diagnostic System

NBHA0014S0808

The 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

=NBHA0015

The 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 Operation

NBHA0016

RHA452GA

IDX

DESCRIPTION

Overview of Control System

HA-23

RHA328HA

DISPLAY SCREEN

NBHA0016S01

Displays the operational status of the system.

AUTO SWITCH

NBHA0016S02

The 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 SWITCH

NBHA0016S03

By 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

NBHA0016S04

Increases or decreases the set temperature.

OFF SWITCH

NBHA0016S05

The 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 SWITCH

NBHA0016S06

Manually 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) SWITCH

NBHA0016S07

OFF position: Outside air is drawn into the passenger compartment.
ON position: Interior air is recirculated inside the vehicle.

DEFROSTER (DEF) SWITCH

NBHA0016S08

Positions the air outlet doors to the defrost position. Also positions the intake doors to the outside air position.

MODE SWITCH

NBHA0016S09

Controls the air discharge outlets.

TEMPERATURE DIAL (POTENTIO TEMPERATURE CONTROL) WITH NAVIGATION SYSTEM

NBHA0016S10

Increases or decreases the set temperature.

AMB (AMBIENT) SWITCH (WITH NAVIGATION SYSTEM)

NBHA0016S11

Shows the ambient (outside) air temperature on the display screen for 5 seconds.

DESCRIPTION

Control Operation (Cont’d)

HA-24

Discharge Air Flow

NBHA0017

RHA043G

IDX

DESCRIPTION

Discharge Air Flow

HA-25

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