sensor INFINITI QX4 2005 Factory Service Manual

PRECAUTIONS
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Revision: October 20052005 QX56
Rear A/C
CAUTION:
The new and former refrigerant connections use different O-ring configurations. Do not confuse O-
rings since they are not interchangeable. If a wrong O-ring is installed, refrigerant will leak at or
around the connection.
1. High-pressure service valve 2. Grommet 3. High-pressure pipe
4. Refrigerant pressure sensor 5. Condenser 6. Compressor shaft seal
7. High-pressure flexible hose 8. Low-pressure flexible hose 9. Low-pressure service valve
10. Low-pressure pipe 11. Expansion valve (front) 12. Drain hose
WJIA2001E
1. Rear A/C pipes 2. Underfloor rear A/C pipes 3. Underfloor rear heater pipes
⇐Front

ATC-18
REFRIGERATION SYSTEM
Revision: October 20052005 QX56
REFRIGERATION SYSTEMPFP:KA990
Refrigerant CycleEJS003X1
REFRIGERANT FLOW
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser with liquid tank,
through the front and rear evaporators, and back to the compressor. The refrigerant evaporation through the
evaporator coils are controlled by front and rear externally equalized expansion valves, located inside the front
and rear evaporator cases.
Refrigerant System ProtectionEJS003X2
REFRIGERANT PRESSURE SENSOR
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sen-
sor, located on the condenser. If the system pressure rises above or falls below the specifications, the refriger-
ant pressure sensor detects the pressure inside the refrigerant line and sends a voltage signal to the ECM.
The ECM de-energizes the A/C relay to disengage the magnetic compressor clutch when pressure on the high
pressure side detected by refrigerant pressure sensor is over about 2,746 kPa (28 kg/cm
2 , 398 psi), or below
about 120 kPa (1.22 kg/cm
2 , 17.4 psi).

ATC-24
AIR CONDITIONER CONTROL
Revision: October 20052005 QX56
AIR CONDITIONER CONTROLPFP:27500
DescriptionEJS003X5
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, also referred to as the front air control, which receives input signals
from the following six sensors:

Ambient sensor

In-vehicle sensor

Intake sensor

Optical sensor (providing one input for driver and one input for passenger side)

PBR (Position Balanced Resistor)

Vehicle speed sensor
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 from rear control
switches located on the front air control, or from the temperature and rear blower settings selected from rear
control switches on the rear air control, when the front air control switches are set to the rear position.
The front air control is used to select:

Outlet air volume

Air temperature/distribution
OperationEJS003X6
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.
BLOWER SPEED CONTROL
Blower speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle tempera-
ture, 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 by the 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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Revision: October 20052005 QX56
MAGNET CLUTCH CONTROL
When A/C switch or DEF switch is pressed, front air control 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 sensor, etc.). If it judges compressor can be turned ON, it sends compressor ON sig-
nal 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.
SELF-DIAGNOSTIC SYSTEM
The self-diagnostic system is built into the front air control to quickly locate the cause of symptoms. Refer to
ATC-55, "
A/C System Self-diagnosis Function"
WJIA1163E

ATC-26
AIR CONDITIONER CONTROL
Revision: October 20052005 QX56
Description of Control SystemEJS003X7
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 OperationEJS003X8
Front air control
WJIA1343E
WJIA1397E

ATC-34
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SELF-DIAGNOSIS
Operation Procedure
1. Touch “SELF-DIAG RESULTS” on “SELECT DIAG MODE”
screen to view all set DTC's.
Display Item List
DATA MONITOR
Operation Procedure
1. Touch “DATA MONITOR” on “SELECT DIAG MODE” screen.
2. Touch either “MAIN SIGNALS” or “SELECTION FROM MENU” on “DATA MONITOR” screen.
3. When “SELECTION FROM MENU” is selected, touch items to be monitored. When “MAIN SIGNALS” is
selected, all the items will be monitored.
4. Touch “START”.
5. Touch “RECORD” while monitoring, then the status of the monitored item can be recorded. To stop
recording, touch “STOP”.
BCIA0031E
DTC Description
Reference page
B2573 Battery voltage out of rangeSC-4, "
BATTERY"
B2578 In-vehicle sensor circuit out of range (low)
ATC-140, "In-vehicle Sensor Circuit"B2579 In-vehicle sensor circuit out of range (high)
B257B Ambient sensor circuit short
ATC-137, "
Ambient Sensor Circuit"B257C Ambient sensor circuit open
B257F Optical sensor (Driver) circuit open or short
ATC-143, "
Optical Sensor Circuit"B2580 Optical sensor (Passenger) circuit open or short
B2581 Intake sensor circuit short
ATC-145, "
Intake Sensor Circuit"B2582 Intake sensor circuit open
U1000 CAN bus faultLAN-5, "
CAN COMMUNICATION"
B2587 Stuck buttonATC-147, "FRONT AIR CONTROL"
BCIA0031E
MAIN SIGNALS Monitors all the items.
SELECTION FROM
MENUSelects and monitors the individual item selected.

TROUBLE DIAGNOSIS
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Revision: October 20052005 QX56
Display Item List
*: DENT is displayed when MODE switch is between selections.
Monitor item Value Contents
BATT VIA CAN "V" Displays battery voltage signal.
IGN VIA CAN "ON/OFF" Displays ignition switch signal.
DVR SUNLD SEN "w/m2" Displays optical sensor (driver) signal.
PAS SUNLD SEN "w/m2" Displays optical sensor (passenger) signal.
AMB TEMP SEN "°C/°F" Displays ambient sensor signal.
EVAP TEMP SEN "°C/°F" Displays intake sensor signal.
INCAR TMP SEN "°C/°F" Displays in-vehicle sensor signal.
RR TEMPSET FR "V" Displays air mix door (front) set point signal.
RR TEMPSET RR "V" Displays air mix door (rear) set point signal.
MODE FDBCK "V" Displays mode door motor feedback signal.
DVR MIX FDBCK "V" Displays air mix door motor (driver) feedback signal.
PAS MIX FDBCK "V" Displays air mix door motor (passenger) feedback signal.
RR FDBCK "V" Displays air mix door motor (rear) feedback signal.
DEF FDBCK "V" Displays defroster door motor feedback signal.
RECIRC "ON/OFF" Displays recirculation switch signal.
DEFROST "ON/OFF" Displays defroster switch signal.
AUTO "ON/OFF" Displays AUTO switch signal.
A/C "ON/OFF" Displays A/C switch signal.
MODE "ON/OFF" Displays MODE switch signal.
L TEMP UP "ON/OFF" Displays driver side temperature control dial (temp increase) signal.
L TEMP DOWN "ON/OFF" Displays driver side temperature control dial (temp decrease) signal.
R TEMP UP "ON/OFF" Displays rear temperature control dial [front (temp increase)] signal.
R TEMP DOWN "ON/OFF" Displays Rear temperature control dial [front (temp decrease)] signal.
RR DEFOG "ON/OFF" Displays rear defroster request signal.
FANUP "ON/OFF" Displays front blower motor (blower speed increase) signal.
FANDOWN "ON/OFF" Displays front blower motor (blower speed decrease) signal.
MODE SELECT" [ PNL ]"
" [ MIX ]"
" [ FLR ]"
" [ DEFR ]"
" [ MAX ]"
" [ DENT ]" Displays mode door motor position.

ATC-40
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
FRONT PASSENGER COMPARTMENT
1. Front air control M49, M50 2. Rear blower switch (front) M52 3. In-vehicle sensor M32
4. Intake sensor M146 5. Intake door motor M58 6. Variable blower control M122
7. Air mix door motor (driver) M147 8. Mode door motor M142 9. Defroster door motor M144
10. Air mix door motor (passenger)
M14311. Optical sensor M402⇐: Front
WJIA1969E

TROUBLE DIAGNOSIS
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Revision: October 20052005 QX56
Front Air Control Terminals and Reference ValueEJS003XJ
Measure voltage between each terminal and ground by following
Terminals and Reference Value for front air control.
PIN CONNECTOR TERMINAL LAYOUT
TERMINALS AND REFERENCE VALUE FOR FRONT AIR CONTROL
WJIA0544E
WJIA0402E
Te r m i -
nal No.Wire
colorItemIgnition
switchConditionVoltage (V)
(Approx.)
1 B Ground - - 0V
2 Y Sensor power ON - 5V
3 W/G Air mix door motor (Driver) CW ON Clockwise rotation Battery voltage
4 G Air mix door motor (Driver) CCW ON Counterclockwise rotation Battery voltage
5 BR/W Mode door motor CW ON Clockwise rotation Battery voltage
6 P/L Mode door motor CCW ON Counterclockwise rotation Battery voltage
7 O Intake door motor CCW ON Counterclockwise rotation Battery voltage
8 G/B Intake door motor CW ON Clockwise rotation Battery voltage
9 L/B Intake sensor ON - 0 - 5V
10 L/R Fan ON signalON Blower switch OFF 5V
ON Blower switch ON 0V
11 Y/B Rear defroster request ON - Battery voltage
12 W/R Compressor ON signalON A/C switch OFF 5V
ON A/C switch ON 0V
13 G/R Variable blower control ON - 0 - 5V
14 Y/G Power supply for IGN ON - Battery voltage
15 P Sensor ground ON - 0V
16 GR Mode door motor feedback ON - 0 - 5V
17 P Ambient sensor ON - 0 - 5V
18 SB Air mix door motor (Driver) feedback ON - 0 - 5V
19 LG Defroster door motor CW ON Clockwise rotation Battery voltage
20 P/B Defroster door motor CCW ON Counterclockwise rotation Battery voltage
21 V/R Sensor return ON - 0 - 5V

ATC-54
TROUBLE DIAGNOSIS
Revision: October 2005 2005 QX56
22 Y/R Power supply for BAT - - Battery voltage
23 R/L Illumination + ON Park lamps ON Battery voltage
24 BR Illumination - - Park lamps ON
25 LG/B Defroster door motor feedback ON - 0 - 5V
26 R/B Front blower request ONFront blower motor OFF Battery voltage
Front blower motor ON 0V
27 GR/R Air mix door motor (Rear) CW ON Clockwise rotation Battery voltage
28 L/Y Air mix door motor (Rear) CCW ON Counterclockwise rotation Battery voltage
29 W/G Water valve ONWater valve open 0V
Water valve closed Battery voltage
31 W/V Optical sensor (Passenger) ON - 0 - 5V
32 LG/R In-vehicle sensor signal ON - 0 - 5V
33 V Air mix door (Rear) set point ON - 0 - 5V
34 L CAN-H ON - 0 - 5V
35 P CAN-L ON - 0 - 5V
36 G/W Air mix door motor (Passenger) CW ON Clockwise rotation Battery voltage
37 LAir mix door motor (Passenger)
CCWON Counter clockwise rotation Battery voltage
38 W/L Rear blower request ONFront blower motor OFF Battery voltage
Front blower motor ON 0V
39 Y/B Rear select signal ON - 0V - Battery voltage
40 G/O Optical sensor (Driver) ON - 0 - 5V
41 R/WAir mix door motor (Passenger)
feedbackON - 0 - 5V
42 R/Y Air mix door motor (Rear) feedback ON - 0 - 5V
43 BR/Y In-vehicle sensor motor (+) ON - Battery voltage
44 O/B In-vehicle sensor motor (-) ON - 0V Te r m i -
nal No.Wire
colorItemIgnition
switchConditionVoltage (V)
(Approx.)
PIIA2344E