2004 INFINITI QX56 speed sensor

ATC-4Revision: August 20072004 QX56 Removal and Installation for Low-pressure Pipe ..171
REMOVAL .........................................................171
INSTALLATION ..................................................171
Removal and Installation for Rear High- and Low-
pressure A/C and Heater Core Pipes ...................171
REMOVAL .........................................................171
INSTALLATION ..................................................172
Removal and Installation for Underfloor Rear High-
and Low-pressure A/C and Heater Core Pipes ....172
REMOVAL .........................................................172
INSTALLATION ..................................................173
Removal and Installation for Refrigerant Pressure
Sensor ..................................................................173
REMOVAL .........................................................173
INSTALLATION ..................................................173
Removal and Installation for Condenser ...............173
REMOVAL .........................................................173
INSTALLATION ..................................................174
Removal and Installation for Front Evaporator .....175
REMOVAL .........................................................175
INSTALLATION ..................................................176
Removal and Installation for Rear Evaporator ......176
REMOVAL .........................................................177INSTALLATION .................................................. 177
Removal and Installation for Front Expansion Valve . 177
REMOVAL .......................................................... 177
INSTALLATION .................................................. 177
Removal and Installation for Rear Expansion Valve . 177
REMOVAL .......................................................... 177
INSTALLATION .................................................. 178
Checking for Refrigerant Leaks ............................ 178
Checking System for Leaks Using the Fluorescent
Dye Leak Detector ................................................ 178
Dye Injection ......................................................... 178
Electronic Refrigerant Leak Detector .................... 179
PRECAUTIONS FOR HANDLING LEAK
DETECTOR ....................................................... 179
CHECKING PROCEDURE ................................ 180
SERVICE DATA AND SPECIFICATIONS (SDS) .... 182
Service Data and Specifications (SDS) ................ 182
COMPRESSOR ................................................. 182
LUBRICANT ....................................................... 182
REFRIGERANT ................................................. 182
ENGINE IDLING SPEED ................................... 182
BELT TENSION ................................................. 182

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.

TROUBLE DIAGNOSIS
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A/C System Self-diagnosis FunctionEJS002CA
DESCRIPTION
Using Front Air Control Switches
NOTE:
Ambient temperature must be at least 10° C (50° F) to run self-diagnosis.
The self-diagnostic system diagnoses sensors, door motors, blower motor, etc. Refer to applicable sections
(items) for details. Shifting from usual control to the self-diagnostic system is accomplished by turning the igni-
tion switch ON and pressing the fan (down) switch while turning the passenger temperature dial in either direc-
tion (hold momentarily). Within 3 seconds of doing this, press the AUTO switch. The front blower speed
indication bars will flash and the ambient temperature display will indicate 0° during the self-diagnosis. Fault
codes (if any are present) will be displayed in the ambient temperature display area. Refer to AT C - 5 5 , "
SELF-
DIAGNOSIS CODE CHART" .
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ATC-84
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:

Front air control

Front blower motor

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control
based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the duty ratio of the blower motor′s drive signal is changed at 8%/sec. to pre-
vent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50°C (122°F), the blower will not
operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies
depending on the ambient and engine coolant temperatures.
In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as
described above. After the coolant temperature reaches 50°C (122°F), or the 210 seconds has elapsed, the
blower speed will increase to the objective blower speed.
Start up from normal operating or hot soak condition (Automatic mode).
The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually
rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
WJIA0440E

TROUBLE DIAGNOSIS
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Ambient Sensor CircuitEJS002CS
COMPONENT DESCRIPTION
Ambient Sensor
The ambient sensor is attached on the radiator core support (left
side). It detects ambient temperature and converts it into a value
which is then input into the front air control.
AMBIENT TEMPERATURE INPUT PROCESS
The front air control includes a processing circuit for the ambient sensor input. However, when the tempera-
ture detected by the ambient sensor increases quickly, the processing circuit retards the front air control func-
tion. It only allows the front air control to recognize an ambient temperature increase of 0.33°C (0.6°F) per 100
seconds.
This prevents constant adjustments due to momentary conditions, such as stopping after high speed driving.
Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor
will increase. This is because the heat from the engine compartment can radiate to the front grille area, loca-
tion of the ambient sensor.
DIAGNOSTIC PROCEDURE FOR AMBIENT SENSOR
SYMPTOM: Ambient sensor circuit is open or shorted. (40 or 41 is
indicated as a result of conducting the front air control self-diagnosis)
1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector E1.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1
terminal 1 (P) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
WJIA0819E
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1 - Ground : Approx. 5V
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ATC-180
REFRIGERANT LINES
Revision: August 20072004 QX56
2. When checking for leaks, circle each fitting completely with the
probe as shown.
3. Move the probe along each component at a speed of approxi-
mately 25 - 50 mm (1 - 2 in)/second as shown.
CHECKING PROCEDURE
NOTE:
To prevent inaccurate or false readings, make sure there is no refrigerant vapor, shop chemicals, or cigarette
smoke in the vicinity of the vehicle. Perform the leak test in a calm area (low air/wind movement) so that the
leaking refrigerant is not dispersed.
1. Turn the engine OFF.
2. Connect the manifold gauge set (J-39183-C) to the A/C service ports. Refer to ATC-162, "
SETTING OF
SERVICE TOOLS AND EQUIPMENT" .
3. Check if the A/C refrigerant pressure is at least 345 kPa (3.52 kg/cm
2 , 50 psi) above a temperature of
16°C (61°F). If less than specification, recover/evacuate and recharge the system with the specified
amount of refrigerant. Refer to ATC-162, "
HFC-134a (R-134a) Service Procedure" .
NOTE:
At temperatures below 16°C (61°F), leaks may not be detected since the system may not reach 345 kPa
(3.52 kg/cm
2 , 50 psi) pressure.
4. Perform the leak test from the high-pressure side (front A/C compressor discharge “a” to evaporator inlet
“f”, or rear piping connection “l”) to the low-pressure side (front A/C evaporator drain hose “g” to shaft seal
“k”, and rear A/C evaporator drain hose “o” to piping connection “r”). Refer to ATC-164, "
Components" .
Clean the component to be checked and carefully move the electronic refrigerant leak detector probe
completely around the following connections and components.

Compressor

Check the high and low-pressure pipe and hose fittings, relief valve, and compressor shaft seal

Check the liquid tank

Check the refrigerant pressure sensor

Check all around the service valves. Check that the service valve caps are tightly screwed on to the
service valves (to prevent leaks).
NOTE:
After removing manifold gauge set (J-39183-C) from the service valves, wipe any residue from the ser-
vice valves to prevent any false readings by the electronic refrigerant leak detector (J-41995).

Evaporator
With engine OFF, turn blower fan on “High” for at least 15 seconds to dissipate any refrigerant trace in
the heater and cooling unit assembly. Wait a minimum of 10 minutes accumulation time (refer to the
manufacturer's recommended procedure for actual wait time) before inserting the electronic refrigerant
leak detector probe into the heater and cooling unit assembly drain hose.
SHA7 06 E
SHA708EA

NAVIGATION SYSTEM
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NAVIGATION SYSTEMPFP:25915
System DescriptionEKS007LI
The navigation system periodically calculates the vehicle's current
position according to the following three signals: Travel distance of
the vehicle as determined by the vehicle speed sensor, turning angle
of the vehicle as determined by the gyroscope (angular velocity sen-
sor), and the direction of vehicle travel as determined by the GPS
antenna (GPS information).
The current position of the vehicle is then identified by comparing the
calculated vehicle position with map data read from the map DVD-
ROM, which is stored in the DVD-ROM drive (map-matching), and
indicated on the screen with a current-location mark.
By comparing the vehicle position detection results found by the
GPS and by map-matching, more accurate vehicle position data can
be used.
The current vehicle position will be calculated by detecting the dis-
tance the vehicle moved from the previous calculation point and its
direction.
TRAVEL DISTANCE
Travel distance calculations are based on the vehicle speed sensor input signal. Therefore, the calculation
may become incorrect as the tires wear down. To prevent this, an automatic distance fine adjustment function
has been adopted. Adjustments can be made in extreme cases (such as driving with tire chain fitted on tires).
Refer to AV-107, "
Confirmation/Adjustment Mode" .
TRAVEL DIRECTION
Change in the travel direction of the vehicle is calculated by a gyroscope (angular velocity sensor) and a GPS
antenna (GPS information). As the gyroscope and GPS antenna have both merit and demerit, input signals
from them are prioritized in each situation. However, this order of priority may change in accordance with more
detailed travel conditions so that the travel direction is detected more accurately.
MAP-MATCHING
Map-matching is a function that repositions the vehicle on the road
map when a new location is judged to be the most accurate. This is
done by comparing the current vehicle position, calculated by the
method described in the position detection principle, with the road
map data around the vehicle, read from the map DVD-ROM stored in
the DVD-ROM drive.
Therefore, the vehicle position may not be corrected after the vehicle
is driven over a certain distance or time in which GPS information is
hard to receive. In this case, the current-location mark on the display
must be corrected manually.
CAUTION:
The road map data is based on data stored in the map DVD-
ROM.
WKIA1371E
SEL684V
Type Advantage Disadvantage
Gyroscope (angular velocity sensor)

Can detect the vehicle's turning angle
quite accurately.
Direction errors may accumulate when the
vehicle is driven for long distances without
stopping.
GPS antenna (GPS information)

Can detect the vehicle's travel direction
(North/South/East/West).
Correct direction cannot be detected when
the vehicle speed is low.
SEL685V

NAVIGATION SYSTEM
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COMPONENT DESCRIPTION
NAVI Control Unit

The gyro (angular speed sensor) and the DVD-ROM drive are
built-in units that control the navigation functions.

Signals are received from the gyro, the vehicle speed sensor,
and the GPS antenna. Vehicle location is determined by com-
bining this data with the data contained in the DVD-ROM map.
Location information is shown on liquid crystal display (display
unit).
DVD-ROM Drive
Maps, traffic control regulations, and other pertinent information can
be easily read from the DVD-ROM disc.
Map DVD-ROM

The map DVD-ROM has maps, traffic control regulations, and other pertinent information.

To improve DVD-ROM map matching and route determination functions, the DVD-ROM uses an exclusive
Nissan format. Therefore, the use of a DVD-ROM provided by other manufacturers cannot be used.
Gyro (Angular Speed Sensor)

The oscillator gyro sensor is used to detect changes in vehicle steering angle.

The gyro is built into the navigation (NAVI) control unit.
BIRDVIEW™
The BIRDVIEW™ provides a detailed and easily seen display of road conditions covering the vehicle's imme-
diate to distant area.

PLAN VIEW
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