2004 INFINITI QX56 air condition

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
WJIA0468E
BCIA0031E
All signals Monitors all the items.
Selection from menu Selects and monitors the individual item selected.
WJIA0469E
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.

TROUBLE DIAGNOSIS
ATC-51
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AT C
Revision: August 20072004 QX56
Front Air Control Terminals and Reference ValueEJS002C9
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
WJIA0759E
WJIA0402E
Te r m i -
nal No.Wire
colorItemIgnition
switchConditionVoltage (V)
(Approx.)
1 B Ground - - 0V
2YPower supply for each door motor
PBRON - 0 - 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 signal ONFan switch OFF 5V
Fan switch ON 0V
11 Y/B Rear defroster request ON - Battery voltage
12 W/R Compressor ON signal ONA/C switch OFF 5V
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 Ground for each door motor PBR ON - 0 - 5V
16 GR Mode door motor PBR feedback ON - 0 - 5V
17 P Ambient sensor ON - 0 - 5V
18 SBAir mix door motor (Driver) PBR
feedbackON - 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

ATC-52
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
21 V/R Sensor ground ON - 0 - 5V
22 Y/R Power supply for BAT - - Battery voltage
23 R/L Power supply for illumination ON Park lamps ON Battery voltage
24 BR Illumination ground - Park lamps ON
25 LG/B Defroster door motor feedback ON - 0 - 5V
26 R/B Front blower motor 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 5V
31 W/V Optical sensor (Passenger) ON - 0 - 5V
32 LG/R In-vehicle sensor signal ON - 0 - 5V
33 V Air mix door motor (Rear) set point ON - 0 - 5V
34 W CAN-H ON - -
35 R CAN-L ON - -
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 motor request ONRear blower motor OFF Battery voltage
Rear blower motor ON 0V
39 Y/B Rear select signal ON - 0 - 5V
40 G/O Optical sensor (Driver) ON - 0 - 5V
41 R/WAir mix door motor (Passenger) PBR
feedbackON - 0 - 5V
42 R/YAir mix door motor (Rear) PBR feed-
backON - 0 - 5V
43 BR/Y In-vehicle sensor motor (power) ON - Battery voltage
44 O/B In-vehicle sensor motor (ground) ON - 0V Te r m i -
nal No.Wire
colorItemIgnition
switchConditionVoltage (V)
(Approx.)
PIIA2344E

ATC-58
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
CHECKING TEMPERATURE INCREASE
1. Rotate temperature dial clockwise (driver or passenger) until
32°C (90°F) is displayed.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-117, "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to ATC-69,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(DRIVER)" or AT C - 7 1 , "DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER)" .
If OK, continue with next check.
CHECK A/C SWITCH
1. Press A/C switch.
2. A/C switch indicator will turn ON.

Confirm that the compressor clutch engages (sound or visual
inspection).
If NG, go to trouble diagnosis procedure for ATC-104, "
Magnet
Clutch Circuit" .
If OK, continue with next check.
CHECKING AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO.

If ambient temperature is warm, and selected temperature is
cool, confirm that the compressor clutch engages (sound or
visual inspection). (Discharge air and blower speed will
depend on ambient, in-vehicle, and set temperatures.)
If NG, go to trouble diagnosis procedure for ATC-60, "
Power Supply
and Ground Circuit for Front Air Control" , then if necessary, trouble
diagnosis procedure for ATC-104, "
Magnet Clutch Circuit" .
If all operational checks are OK (symptom cannot be duplicated), go
to malfunction Simulation Tests in AT C - 3 5 , "
How to Perform Trouble
Diagnosis for Quick and Accurate Repair" and perform tests as out-
lined to simulate driving conditions environment. If symptom appears. Refer to ATC-35, "
How to Perform Trou-
ble Diagnosis for Quick and Accurate Repair" , AT C - 3 5 , "SYMPTOM TABLE" and perform applicable trouble
diagnosis procedures.
WJIA0409E
WJIA0410E
WJIA0411E

TROUBLE DIAGNOSIS
ATC-59
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AT C
Revision: August 20072004 QX56
Operational Check (Rear)EJS002CC
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear fan switch (front) clockwise to "1". The rear blower
should operate on low speed.
2. Turn the rear fan switch (front) clockwise again to switch position
"2", "3", and "4" until all speeds are checked.
3. Leave blower on maximum speed.
If NG, go to trouble diagnosis procedure for AT C - 9 0 , "
Rear Blower
Motor Circuit" .
If OK, continue with next check.
CHECKING TEMPERATURE DECREASE
1. Rotate rear temperature/mode dial (front) fully counterclockwise.
2. Check for cold air at appropriate discharge air outlets (headliner
outlets).
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for AT C - 11 0 , "
Insufficient Cooling" . If
air mix door motor appears to be malfunctioning, go to AT C - 7 3 ,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue with next check.
CHECKING TEMPERATURE INCREASE
1. Rotate rear temperature/mode dial (front) clockwise.
2. Check for hot air at appropriate discharge air outlets (floor out-
lets).
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for AT C - 11 7 , "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to AT C - 7 3 ,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue with next check.Conditions : Engine running and at normal operating temperature
WJIA0838E
WJIA0626E
WJIA0627E

TROUBLE DIAGNOSIS
ATC-61
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AT C
Revision: August 20072004 QX56
COMPONENT DESCRIPTION
Front Air Control
The front air control has a built-in microcomputer which processes
information sent from various sensors needed for air conditioner
operation. The air mix door motors, mode door motor, intake door
motor, defroster door motor, blower motor and compressor are then
controlled.
The front air control is unitized with control mechanisms. When the
various switches and temperature dials are operated, data is input to
the front air control.
Self-diagnostic functions are also built into the front air control to pro-
vide quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
There are two PTCs (passenger and driver) built into the front air
control. They can be set at an interval of 0.5°C (1.0°F) in the 18°C
(65°F) to 30°C (85°F) temperature range by rotating the temperature
dial. The set temperature is displayed.
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM
SYMPTOM: A/C system does not come on.
WJIA0759E
WJIA0413E
WJIA0414E

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
ATC-85
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Revision: August 20072004 QX56
Blower Speed Compensation - Sunload
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The speed will vary depending on the sunload. During conditions of low or no sunload, the blower
operates at low speed. During high sunload conditions, the front air control causes the blower speed to
increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the front heater and cooling
unit. The variable blower control receives a gate voltage from the
front air control to steplessly maintain the blower motor voltage in the
0 to 5 volt range (approx.).
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning under starting
blower speed control.
WJIA0441E
WJIA0559E
WJIA0778E