Air INFINITI QX56 2004 Factory Service Manual

ATC-24
AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
AIR CONDITIONER CONTROLPFP:27500
DescriptionEJS002BW
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 that is part of the front air control, which receives input signals from
the following five sensors:

Ambient sensor

In-vehicle sensor

Intake sensor

Optical sensor (one sensor for driver and passenger side)

PBR (position balanced resistor)
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 on the front air control
rear fan switch (front) and rear temperature/mode dial (front), or from the rear fan switch (rear) and rear tem-
perature/mode dial (rear) on the rear air control, when the rear fan switch (front) is set to the rear (R) position.
The front air control or rear air control is used to select:

Outlet air volume

Air temperature/mode distribution
OperationEJS002BX
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.
FAN SPEED CONTROL
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle tem-
perature, 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 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 the A/C or DEF switch is activated, the front air control outputs a compressor ON signal to the BCM.
Upon receiving this input, the BCM sends a compressor ON signal to the ECM via CAN communication lines.
The ECM then judges whether the compressor can be turned ON, based on each sensor status (refrigerant
pressure sensor signal, throttle angle sensor, etc.). If it determines the compressor can be turned ON, a com-
pressor ON signal is sent to the IPDM E/R via CAN communication lines.
Upon receipt of a compressor ON signal, the IPDM E/R turns ON the A/C relay which engages the magnet
clutch and operates the A/C compressor.
SELF-DIAGNOSTIC SYSTEM
A self-diagnostic system is built into the front air control to quickly locate the cause of symptoms. Refer to
ATC-53, "
A/C System Self-diagnosis Function"
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ATC-26
AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
Description of Control SystemEJS002BY
The control system consists of input sensors, switches, the front air control (microcomputer) and outputs.
The relationship of these components is shown in the figure below:
Control OperationEJS002BZ
Front air control
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AIR CONDITIONER CONTROL
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DISPLAY SCREEN
Displays the operational status of the system.
AUTO SWITCH

The compressor, intake door, air mix doors, 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 oper-
ator.
TEMPERATURE DIAL (DRIVER)
Increases or decreases the driver zone temperature.
TEMPERATURE DIAL (PASSENGER)
Increases or decreases the passenger zone temperature.
RECIRCULATION SWITCH ()

When pressed an indicator turns ON in the display, and air inlet is set to recirculation mode.

Recirculation mode is cancelled by pressing the switch again, turning ON the front defroster, pressing the
OFF switch, or pressing the A/C switch to turn off the A/C system and compressor.
DEFROSTER () SWITCH
Positions the air outlet doors to the defrost position. Also positions the intake door to the outside air position.
REAR WINDOW DEFOGGER SWITCH
When switch is ON, rear window is defogged.
OFF SWITCH (HOLD FAN DOWN SWITCH UNTIL SYSTEM SHUTS OFF)
The compressor and blower are OFF, the intake door is set to the outside air position, and the air outlet doors
are set to the foot (75% foot and 25% defrost) position.
A/C SWITCH
The compressor is ON or OFF.
(Pressing the A/C switch when the AUTO switch is ON will turn off the A/C switch and compressor.)
MODE SWITCH
Controls the air discharge outlets.
FRONT FAN SWITCH
Manually controls the blower speed. Seven speeds are available for manual control (as shown on the display
screen).
REAR FAN SWITCH (FRONT)
Manually controls the rear blower speed. Four speeds are available for manual control. When the rear fan
switch (front) is in the off (0) position, the rear blower motor cannot operate. Position (R) allows control of rear
blower speed and rear temperature/mode operation to be transferred to rear air control.
REAR TEMPERATURE/MODE DIAL (FRONT)
Increases or decreases the rear zone temperature and adjusts the mode simultaneously. FLOOR is full hot
setting, FLOOR/PANEL is warm setting, and PANEL is full cold setting.

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AIR CONDITIONER CONTROL
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Rear Air Control
REAR TEMPERATURE/MODE DIAL (REAR)
Increases or decreases the rear zone temperature and adjusts the mode simultaneously. FLOOR is full hot
setting, FLOOR/PANEL is warm setting, and PANEL is full cold setting. Operates only with rear fan switch
(front) is in the (R) position.
REAR FAN CONTROL SWITCH (REAR)
When the rear fan switch (front) is in the (R) position, it allows the rear fan switch (rear) to control the blower
motor speed. In any other position (1-4), the rear fan switch (front) controls the rear blower motor speed
regardless of the rear fan switch (rear) position.
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AIR CONDITIONER CONTROL
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Discharge Air FlowEJS002C0
FRONT
REAR
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AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
System Description (Front)EJS002C1
CONTROLS AND THEIR FUNCTIONS
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AIR CONDITIONER CONTROL
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System Description (Rear)EJS002C2
CONTROLS AND THEIR FUNCTIONS
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ATC-32
AIR CONDITIONER CONTROL
Revision: August 20072004 QX56
CAN Communication System DescriptionEJS002C3
Refer to LAN-5, "CAN COMMUNICATION" .

ATC-34
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
DATA MONITOR
Operation Procedure
1. Touch “AIR CONDITIONER” on “SELECT TEST ITEM” screen.
2. Touch “DATA MONITOR” on “SELECT DIAG MODE” screen.
3. Touch either “ALL SIGNALS” or “SELECTION FROM MENU” on
“DATA MONITOR” screen.
4. Touch “START”.
5. When “SELECTION FROM MENU” is selected, touch items to
be monitored. When “ALL SIGNALS” is selected, all the items
will be monitored.
6. Touch “RECORD” while monitoring, then the status of the moni-
tored item can be recorded. To stop recording, touch “STOP”.
Display Item List
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All signals Monitors all the items.
Selection from menu Selects and monitors the individual item selected.
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Monitor item name “operation or
unit”Contents
IGN ON SW “ON/OFF” Displays “IGN Position (ON)/OFF, ACC Position (OFF)” status as judged from ignition switch signal.
COMP ON SIG “ON/OFF” Displays “COMP (ON)/COMP (OFF)” status as judged from air conditioner switch signal.
FAN ON SIG “ON/OFF” Displays “FAN (ON)/FAN (OFF)” status as judged from blower motor switch signal.