air condition INFINITI QX56 2007 Factory Service Manual

TROUBLE DIAGNOSISATC-51
< SERVICE INFORMATION >
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1. Rotate temperature control dial (driver si de or passenger side) counterclockwise until 16 °C (60 °F) is dis-
played.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operat ion. If OK, go to trouble diagnosis procedure for ATC-100,
"Insufficient Cooling" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" or ATC-59, "Air Mix Door Motor Circuit".
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockw ise (driver side or passenger side) 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 operat ion. If OK, go to trouble diagnosis procedure for ATC-108,
"Insufficient Heating" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" or ATC-59, "Air Mix Door Motor Circuit".
If OK, continue with next check.
CHECK A/C SWITCH
1. Press A/C switch when AUTO switch is ON, or in manual mode.
2. A/C switch indicator will turn ON.
• Confirm that the compressor clutch engages (sound or visual inspection).
NOTE:
If current mode setting is DEF or D/F, compressor clutch may already be engaged.
If NG, go to trouble diagnosis procedure for ATC-96, "
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 temperat ure is cool, confirm that the compressor clutch
engages (sound or visual inspection). (Discharge air and blower speed will depend on ambient, in-vehi-
cle, and set temperatures.)
If NG, go to trouble diagnosis procedure for ATC-52, "
Power Supply and Ground Circuit for Front Air Control" ,
then if necessary, trouble diagnosis procedure for ATC-96, "
Magnet Clutch Circuit" .
If all operational checks are OK (symptom cannot be duplicated), go to malfunction Simulation Tests in AT C -
32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" and perform tests as outlined to simu-
late driving conditions environment . If symptom appears. Refer to ATC-32, "
How to Perform Trouble Diagnosis
for Quick and Accurate Repair", ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair"
and perform applicable trouble diagnosis procedures.
Operational Check (Rear)INFOID:0000000003533250
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear blower control dial to swit ch position "1". Blower should operate on low speed.
2. Turn the rear blower control dial counterclockwis e to switch position "2", "3", and "4" until all speeds are
checked.
3. Leave blower on MAX speed.
If NG, go to trouble diagnosis procedure for ATC-85, "
Rear Blower Motor Circuit" .
If OK, continue the check.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature and mode dial fully counterclockwise.
2. Check for cold air at appropriate discharge air outlets. Conditions : Engine running and at normal operating temperature

ATC-52
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
If NG, listen for sound of air mix door motor operation if OK, go to trouble diagnosis procedure for ATC-100,
"Insufficient Cooling" . If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit".
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature and mode dial clockwise.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operat ion. If OK, go to trouble diagnosis procedure for ATC-108,
"Insufficient Heating". If air mix door motor appears to be malfunctioning, go to ATC-59, "Air Mix Door Motor
Circuit" .
If OK, continue the check.
Power Supply and Ground Circu it for Front Air ControlINFOID:0000000003533251
SYMPTOM: A/C system does not come on.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO. Confirm that the compressor clutch engages (sound or visual inspection).
(Discharge air and blower speed will depend on am bient, in-vehicle and set temperatures.)
Can a symptom be duplicated?
YES >> GO TO 3.
NO >> GO TO 2.
2.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Refer to ATC-50, "
Operational Check
(Front)".
Can a symptom be duplicated
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair".
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK POWER AND GROUND CIRCUIT
Check main power supply and ground circuit. Refe r to "DIAGNOSTIC PROCEDURE FOR A/C SYSTEM".
OK or NG
OK >> System OK.
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
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.
WJIA0544E

ATC-56
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Mode Door Control Specification
COMPONENT DESCRIPTION
Mode Door Motor
The mode door motor is attached to the heater & cooling unit. It
rotates so that air is discharged from the outlet as indicated by the
front air control. Motor rotation is conveyed to a link which activates
the mode door.
DIAGNOSTIC PROCEDURE FOR MODE DOOR MOTOR
1.CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the mode switch to the B/L ( ) mode.
3. Check voltage between front air control harness connector M49 terminal 5 and terminal 6 while pressing the mode switch to the
floor ( ) mode.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK MODE DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 5, 6 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR GROUND AND POWER
WJIA0434E
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Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 6 5 Press
mode
switch Battery
voltage
WJIA1727E
5 - Ground : Continuity should not exist.
6 - Ground : Continuity should not exist.
WJIA1734E

TROUBLE DIAGNOSISATC-57
< SERVICE INFORMATION >
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1. Press the mode switch to the D/F ( ) mode.
2. Check voltage between front air control harness connector M49 terminal 5 and terminal 6 while pressing the mode switch to the
vent ( ) mode.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation" .
4.CHECK MODE DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 5 and terminal 6.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.CHECK MODE DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the mode door motor harness connector.
2. Check continuity between front air control harness connector
M49 terminal 5, 6 and the mode door motor harness connector
terminal 5, 6.
OK or NG
OK >> Replace mode door motor. Refer to ATC-140, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
6.CHECK FRONT AIR CONTROL FOR PBR POWER AND GROUND
1. Reconnect front air control harness connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 2 and terminal 15.
OK or NG
OK >> GO TO 8.
NG >> GO TO 7.
7.CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 5 6 Press
mode
switch Battery
voltage
WJIA1742E
Continuity should exist.
WJIA1728E
5 - 5 : Continuity should exist.
6 - 6 : Continuity should exist.
LJIA0027E
Connector Te r m i n a l s
Voltage (Ap-
prox.)
(+) (-)
Front air control: M49 2 15 5V
WJIA1729E

ATC-62
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch ON.
2. Rotate temperature control dial (driver) to 32°C (90 °F).
3. Check voltage between front air control harness connector M49
terminal 3 and terminal 4 while rotating temperature control dial
(driver) to 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK AIR MIX DOOR MOTOR (DRIVE R) CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 3, 4 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Rotate temperature control dial (driver) to 32 °C (90 °F).
3. Check voltage between front air control harness connector M49
terminal 3 and terminal 4 while rotating temperature control dial
(driver) to 16 °C (60 °F).
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation" .
4.CHECK AIR MIX DOOR MOTOR (DRIVER) CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 3 and terminal 4.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.CHECK AIR MIX DOOR MOTOR ( DRIVER) CIRCUITS FOR OPEN
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 3 4 Rotate temp
control dial Battery
voltage
WJIA1735E
3 - Ground : Continuity should not exist.
4 - Ground : Continuity should not exist.
WJIA1736E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 4 3
Rotate temp
control dial Battery
voltage
WJIA1737E
Continuity should exist.
WJIA1738E

TROUBLE DIAGNOSISATC-65
< SERVICE INFORMATION >
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1. Turn ignition switch ON.
2. Rotate temperature control dial (passenger) to 32 °C (90 °F).
3. Check voltage between front air control harness connector M50
terminal 36 and terminal 37 while rotating temperature control
dial (passenger) to 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK AIR MIX DOOR MOTOR (PASSENG ER) CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M50 terminal 36, 37 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Rotate temperature control dial (passenger) to 16 °C (60 °F).
3. Check voltage between front air control harness connector M50
terminal 36 and terminal 37 while rotating temperature control
dial (passenger) to 32 °C (90 °F).
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
4.CHECK AIR MIX DOOR MOTOR (PASSENGER) CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M50 terminal 36 and terminal 37.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.CHECK AIR MIX DOOR MOTOR (P ASSENGER) CIRCUITS FOR OPEN
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M50 37 36 Rotate temp
control dial Battery
voltage
WJIA1740E
36 - Ground : Continuity should not exist.
37 - Ground : Continuity should not exist.
WJIA1741E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M50 36 37
Rotate temp
control dial Battery
voltage
WJIA1778E
Continuity should exist.
WJIA1779E

ATC-68
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch ON.
2. Rotate temperature control dial (rear) to maximum heat.
3. Check voltage between front air control harness connector M50terminal 27 and terminal 28 while rotating temperature control
dial (rear) to maximum cold.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK AIR MIX DOOR MOTOR (REAR) CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M50 terminal 27, 28 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Rotate temperature control dial (rear) to maximum cold.
3. Check voltage between front air control harness connector M50 terminal 27 and terminal 28 while rotating temperature control
dial (rear) to maximum heat.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
4.CHECK AIR MIX DOOR MOTOR (REAR) CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M50 terminal 27 and terminal 28.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.CHECK AIR MIX DOOR MOTOR (REAR) CIRCUITS FOR OPEN
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M50 27 28 Rotate temp
control dial Battery
voltage
WJIA1744E
27 - Ground : Continuity should not exist.
28 - Ground : Continuity should not exist.
WJIA1745E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M50 28 27
Rotate temp
control dial Battery
voltage
WJIA1746E
Continuity should exist.
WJIA1747E

TROUBLE DIAGNOSISATC-73
< SERVICE INFORMATION >
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1. Turn ignition switch ON.
2. Check voltage between front air control harness connector M49 terminal 7 and terminal 8 while placing the HVAC system into
self-diagnostic mode.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK INTAKE DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 7, 8 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation".
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the BACK button to back out of self-diagnostic mode.
2. Check voltage between front air control harness connector M49 terminal 7 and terminal 8 while placing the HVAC system into
self-diagnostic mode.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation" .
4.CHECK INTAKE DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 7 and terminal 8.
OK or NG
OK >> Replace intake door motor. Refer to ATC-139, "Removal
and Installation".
NG >> GO TO 5.
5.CHECK INTAKE DOOR MOTOR CIRCUITS FOR OPEN
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 7 8 Self-diagnostic
mode Battery volt-
age
WJIA1757E
7 - Ground : Continuity should not exist.
8 - Ground : Continuity should not exist.
WJIA1758E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 8 7 Self-diagnostic
mode Battery
voltage
WJIA1759E
Continuity should exist.
WJIA1760E

ATC-76
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 19, 20 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation".
NG >> Repair or replace harness as necessary.
3.CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the defroster switch ( ).
2. Check voltage between front air control harness connector M49 terminal 19 and terminal 20 and pr ess the defroster switch ( )
again.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
4.CHECK DEFROSTER DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector M49 terminal 19 and terminal 20.
OK or NG6
OK >> GO TO 6.
NG >> GO TO 5.
5.CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR OPEN
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 20 19 Press de-
froster
switch Battery
voltage
19 - Ground : Continuity should not exist.
20 - Ground : Continuity should not exist.
WJIA1766E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Front air control: M49 19 20 Press de-
froster
switch Battery
voltage
WJIA1767E
Continuity should exist.
WJIA1773E

ATC-80
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
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 sens or, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the blower motor s peed is adjusted gradually to prevent a sudden increase in
air flow.
In addition to manual air flow control and the usual automat ic air flow control, starting air flow control, low
water temperature starting control and high passenger co mpartment 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 temper ature) 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 usual 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).
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
WJIA1357E
WJIA0441E