2007 INFINITI QX56 Factory Service Manual

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Page 449 of 3061

INFINITI QX56 2007 Factory Service Manual
TROUBLE DIAGNOSISATC-79
< SERVICE INFORMATION >
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1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - FRONT BLOWER
1. Rotate the front blower control dial clockwise. B

TROUBLE DIAGNOSISATC-79
< SERVICE INFORMATION >
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1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - FRONT BLOWER
1. Rotate the front blower control dial clockwise. Blower should operate.
2. Rotate the front blower control dial clockwise, and continue checking blower speed and fan symbol until
all speeds are checked.
Can the symptom be duplicated?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to ATC-50, "
Operational Check (Front)" .
Does another symptom exist?
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.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
Are any self-diagnosis codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function" .
NO >> GO TO 5.
5.CHECK BLOWER MOTOR OPERATION
Check and verify blower motor operates manually in all speeds.
Does blower motor operate in all speeds?
YES >> GO TO 6.
NO >> Refer to "DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR".
6.CHECK ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT
Check engine coolant temperature sensor circuit. Refer to EC-205
.
OK or NG?
OK >> GO TO 7.
NG >> Refer to EC-207, "
Diagnosis Procedure".
7.RECHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to ATC-50, "
Operational Check (Front)" .
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" .
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:• Front air control
• Variable blower control
• Front blower motor relay
• Front blower motor
• In-vehicle sensor
• Ambient sensor
• Optical sensor
• Intake sensor

Page 450 of 3061

INFINITI QX56 2007 Factory Service Manual
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

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

Page 451 of 3061

INFINITI QX56 2007 Factory Service Manual
TROUBLE DIAGNOSISATC-81
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COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the cooling unit. The vari-
a

Page 452 of 3061

INFINITI QX56 2007 Factory Service Manual
ATC-82
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect front blower motor connector.
3. Turn ignition switch ON.
4. Press the mode switch to select any mode excep

Page 453 of 3061

INFINITI QX56 2007 Factory Service Manual
TROUBLE DIAGNOSISATC-83
< SERVICE INFORMATION >
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7.CHECK VARIABLE BLOWER CONTROL SIGNAL CIRCUIT
1. Disconnect front air control connector.
2. Check continuity between

Page 454 of 3061

INFINITI QX56 2007 Factory Service Manual
ATC-84
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect front blower motor connector and variable blowercontrol connector.
3. Check continuity between variable blo

Page 455 of 3061

INFINITI QX56 2007 Factory Service Manual
TROUBLE DIAGNOSISATC-85
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Check continuity between terminals by supplying 12 volts and
ground to coil side terminals of relay.
Front Blower Mot

Page 456 of 3061

INFINITI QX56 2007 Factory Service Manual
ATC-86
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Perform a complete operational check for any symptoms. Refer to ATC-50, "Operational Check (Front)".
Does another symptom exist?
YES >> Refer to ATC-

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