control INFINITI FX35 2004 Service Manual

ATC-30
AIR CONDITIONER CONTROL
Revision: 2004 November 2004 FX35/FX45
AIR CONDITIONER CONTROLPFP:27500
Description of Air Conditioner LAN Control SystemAJS0014A
The LAN (Local Area Network) system consists of unified meter and A/C amp., mode door motor, air mix door
motor and intake door motor.
A configuration of these components is shown in the diagram below.
System ConstructionAJS0014B
A small network is constructed between the unified meter and A/C amp., air mix door motor, mode door motor
and intake door motor. The unified meter and A/C amp. and motors are connected by data transmission lines
and motor power supply lines. The LAN network is built through the ground circuits of the each door motor.
Addresses, motor opening angle signals, motor stop signals and error checking messages are all transmitted
through the data transmission lines connecting the unified meter and A/C amp. and each door motor.
The following functions are contained in LCUs built into the air mix door motor, mode door motor and intake
door motor.

Address

Motor opening angle signals

Data transmission

Motor stop and drive decision

Opening angle sensor (PBR function)

Comparison

Decision (Unified meter and A/C amp. indicated value and motor opening angle comparison)
OPERATION
The unified meter and A/C amp. receives data from each of the sensors. The unified meter and A/C amp.
sends mode door, air mix door and intake door opening angle data to the mode door motor LCU, air mix door
motor LCU and intake door motor LCU.
The mode door motor, air mix door motor and intake door motor read their respective signals according to the
address signal. Opening angle indication signals received from the unified meter and A/C amp. and each of
the motor position sensors are compared by the LCUs in each motor with the existing decision and opening
angles. Subsequently, HOT/COLD, DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The
new selection data is returned to the unified meter and A/C amp.
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AIR CONDITIONER CONTROL
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TRANSMISSION DATA AND TRANSMISSION ORDER
Unified meter and A/C amp. data is transmitted consecutively to each of the door motors following the form
shown in figure below.
Start:
Initial compulsory signal sent to each of the door motors.
Address:
Data sent from the unified meter and A/C amp. is selected according to data-based decisions made by the air
mix door motor, mode door motor and intake door motor.
If the addresses are identical, the opening angle data and error check signals are received by the door motor
LCUs. The LCUs then make the appropriate error decision. If the opening angle data is usual, door control
begins.
If an error exists, the received data is rejected and corrected data received. Finally, door control is based upon
the corrected opening angle data.
Opening Angle:
Data that shows the indicated door opening angle of each door motor.
Error Check:
Procedure by which sent and received data is checked for errors. Error data is then compiled. The error check
prevents corrupted data from being used by the air mix door motor, mode door motor and intake door motor.
Error data can be related to the following symptoms.

Unusual electrical frequency

Poor electrical connections

Signal leakage from transmission lines

Signal level fluctuation
RJIA1748E

ATC-32
AIR CONDITIONER CONTROL
Revision: 2004 November 2004 FX35/FX45
Stop Signal:
At the end of each transmission, a stop operation, in-operation, or internal error message is delivered to the
unified meter and A/C amp. This completes one data transmission and control cycle.
AIR MIX DOOR CONTROL (AUTOMATIC TEMPERATURE CONTROL)
The air mix door is 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 by temperature setting, ambient temperature, in-vehicle temperature,
intake temperature, amount of sunload and air mix door position.
When pressing AUTO switch, 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
The intake doors are automatically controlled by the temperature setting, ambient temperature, in-vehicle tem-
perature, intake temperature, amount of sunload and ON-OFF operation of the compressor.
OUTLET DOOR CONTROL
The outlet door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temper-
ature, intake temperature and amount of sunload.
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AIR CONDITIONER CONTROL
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Revision: 2004 November 2004 FX35/FX45
MAGNET CLUTCH CONTROL
When A/C switch or DEF switch is pressed, unified meter and A/C amp. 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, etc.). If it judges compressor can be turned ON, it sends compressor ON signal 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.
When sending compressor ON signal to IPDM E/R via CAN communication line, ECM simultaneously sends
compressor feedback signal to unified meter and A/C amp. via CAN communication line.
Unified meter and A/C amp, then, uses input compressor feedback signal to control air inlet.
SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the unified meter and A/C amp. to quickly locate the cause of symp-
toms.
RJIA1957E

ATC-34
AIR CONDITIONER CONTROL
Revision: 2004 November 2004 FX35/FX45
Description of Control SystemAJS0014C
The control system consists of input sensors, switches, the unified meter and A/C amp. (microcomputer) and
outputs.
The relationship of these components is shown in the figure below:
Control OperationAJS0014D
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RJIA1959E

AIR CONDITIONER CONTROL
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DISPLAY SCREEN
Displays the operational status of the system.
AUTO SWITCH

The compressor, intake doors, 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
operator.

When pressing AUTO switch, air inlet, air outlet, fan speed, and discharge air temperature are automati-
cally controlled.
TEMPERATURE SWITCH (POTENTIO TEMPERATURE CONTROL) (DRIVER SIDE)
Increases or decreases the set temperature.
TEMPERATURE SWITCH (POTENTIO TEMPERATURE CONTROL) (PASSENGER SIDE)

Increases or decreases the set temperature.

When the temperature switch is pressed, the dual switch indicator will automatically illuminate.
RECIRCULATION (REC) SWITCH

When REC switch is ON, REC switch indicator turns ON, and air inlet is fixed to REC.

When REC switch is ON and is pressed for approximately 1.5 seconds or longer, REC and FRE switch
indicators blink twice. Then, automatic control mode is entered. Inlet status is displayed even during auto-
matically controlled.

When FRE switch is turned ON, or when compressor is turned from ON to OFF, REC switch is automati-
cally turned OFF (fixed to FRE mode). REC mode can be re-entered by pressing REC switch again.

REC switch is not operated when DEF switch is turned ON, or at the D/F position.
FRESH (FRE) SWITCH

When FRE switch is ON, FRE switch indicator turns ON, and air inlet is fixed to FRE.

When FRE switch is ON and is pressed for approximately 1.5 seconds or longer, REC and FRE switch
indicators blink twice. Then, automatic control mode is entered. Inlet status is displayed even during auto-
matically controlled.

When REC switch is turned ON, FRE switch is automatically turned OFF (fixed to REC mode). FRE mode
can be re-entered by pressing FRE switch again.
DEFROSTER (DEF) SWITCH
Positions the air outlet doors to the defrost position. Also positions the intake doors to the fresh air position.
REAR WINDOW DEFOGGER SWITCH
When illumination is ON, rear window is defogged.
OFF SWITCH
The compressor and blower are OFF, the intake doors are set to the fresh 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.
FAN SWITCH
Manually control the blower speed. Seven speeds are available for manual control (as shown on the display
screen).
DUAL SWITCH (WITH LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CON-
TROL SYSTEM)

When the DUAL switch indicator is not illuminated and the DUAL switch is pressed, the driver-side setting
temperature and passenger-side setting temperature can each be set independently.

When the DUAL switch indicator is illuminated and the DUAL switch is pressed, the driver-side setting
temperature are applied to both sides.

ATC-36
AIR CONDITIONER CONTROL
Revision: 2004 November 2004 FX35/FX45
Fail-safe FunctionAJS0014E

If a communication error exists between unified meter and A/C amp. and A/C and AV switch for 30 sec-
onds or longer, air conditioner is controlled under following conditions:
–Compressor: ON
–Air outlet: AUTO
–Air inlet: FRE (Fresh)
–Blower fan speed: AUTO
–Set temperature: Setting before communication error occurs

AIR CONDITIONER CONTROL
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Discharge Air FlowAJS0014F
RJIA1960E

ATC-38
AIR CONDITIONER CONTROL
Revision: 2004 November 2004 FX35/FX45
System DescriptionAJS0014G
SWITCHES AND THEIR CONTROL FUNCTION
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RJIA1962E

AIR CONDITIONER CONTROL
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Revision: 2004 November 2004 FX35/FX45
CAN Communication System DescriptionAJS0014H
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. For details, refer to LAN-6,
"CAN Communication Unit" .