2008 INFINITI QX56 air condition

HAC-44
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
DEFROSTER DOOR MOTOR CIRCUIT
DEFROSTER DOOR
MOTOR CIRCUIT
System DescriptionINFOID:0000000001679792
SYSTEM DESCRIPTION
Component Parts
Defroster door control system components are:• A/C auto amp.
• A/C and AV switch assembly
• Defroster door motor
• PBR (Built into defroster door motor)
• In-vehicle sensor
• Ambient sensor
• Optical sensor
• Intake sensor
System Operation
The A/C auto amp. determines defroster door position bas ed on the position of the defroster switch. When the
defroster switch is depressed, the defroster door motor rotates directing air to the defroster ducts. When any
mode other than defroster is selected, the defroster moto r rotates in the opposite direction closing off air flow
to the defroster ducts.
In the AUTO mode, the A/C auto amp. determines def roster door position based on the ambient temperature,
the intake air temperature and the in-vehicle temperature.
COMPONENT DESCRIPTION
Defroster door motor
The defroster door motor is attached to the front heater & cooling
unit assembly. The A/C auto amp. sends a voltage to rotate to the
defroster door directing the air flow either to the defroster ducts, or to
the floor ducts, depending on which way the voltage and ground are
applied to the motor leads. Motor rotation is conveyed to a lever
which activates the defroster door.
AWIIA0151GB
WJIA0592E
Revision: March 2010 2008 QX56

DEFROSTER DOOR MOTOR CIRCUITHAC-45
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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Defroster Door Motor Co mponent Function CheckINFOID:0000000001679793
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING O PERATIONAL CHECK - DEFROSTER DOOR
1. Press the mode switch and select vent ( ).
2. Press the defrost switch ( ). Defroster indicator should illuminate (on display).
3. Listen for defroster door position change (blower sound should change slightly).
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 HAC-4, "
Operational Check (Front)".
Does another symptom exist?
YES >> Refer to HAC-3, "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 DEFROSTER DOOR MOTOR
Perform diagnostic procedure for defroster door motor. Refer to HAC-45, "
Defroster Door Motor Component
Function Check".
Is the inspection result normal?
YES >> GO TO 5.
NO >> Repair PBR circuit or replace defroster door motor. Refer to VTL-21, "
Removal and Installation".
5.CHECK DEFROSTER DOOR OPERATION
Check and verify defroster door mechanism for smooth operation.
Is the inspection result normal?
YES >> Replace defroster door motor. Refer to VTL-21, "Removal and Installation".
NO >> Repair defroster door mechanism.
Defroster Door Motor Diagnosis ProcedureINFOID:0000000001679794
SYMPTOM:
• Defroster door does not change.
• Defroster door motor does not operate normally.
DIAGNOSTIC PROCEDURE FOR DEFROSTER DOOR MOTOR
1.CHECK A/C AUTO AMP. FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the defroster switch ( ).
3. Check voltage between A/C auto amp. harness connector M49 terminal 24 and terminal 23 and press the defroster switch ( )
again.
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
A/C auto amp.: M49 24 23 Press de-
froster switch Battery
voltage
AWIIA0152ZZ
Revision: March 2010 2008 QX56

HAC-46
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
DEFROSTER DOOR MOTOR CIRCUIT
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connector.
3. Check continuity between A/C auto amp. harness connector M49 terminal 23, 24 and ground.
Is the inspection result normal?
YES >> Replace A/C auto amp. Refer to VTL-7, "Removal and
Installation".
NO >> Repair or replace harness as necessary.
3.CHECK A/C AUTO AMP. FOR GROUND AND POWER
1. Press the defroster switch ( ).
2. Check voltage between A/C auto amp. harness connector M49 terminal 23 and terminal 24 and pr ess the defroster switch ( )
again.
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace A/C auto amp. Refer to VTL-7, "
Removal and Installation".
4.CHECK DEFROSTER DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connector.
3. Check continuity between A/C auto amp. harness connector M49 terminal 23 and terminal 24.
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5.CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the defroster door motor harness connector.
2. Check continuity between A/C auto amp. harness connector M49 (A) terminal 23, 24 and the defroster door motor harness
connector M144 (B) terminal 1, 6.
Is the inspection result normal?
YES >> Replace defroster door motor. Refer to VTL-21,
"Removal and Installation".
23 - Ground : Continuity should not exist.
24 - Ground : Continuity should not exist.
AWIIA0153ZZ
Connector
Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
A/C auto amp.: M49 23 24 Press de-
froster
switch Battery
voltage
AWIIA0154ZZ
Continuity should exist.
AWIIA0155ZZ
23 - 1 : Continuity should exist.
24 - 6 : Continuity should exist.
AWIIA0156ZZ
Revision: March 2010 2008 QX56

DEFROSTER DOOR MOTOR CIRCUITHAC-47
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NO >> Repair or replace harness as necessary.
6.CHECK A/C AUTO AMP. FOR PBR POWER AND GROUND
1. Reconnect A/C auto amp. harness connector.
2. Turn ignition switch ON.
3. Check voltage between A/C auto amp. harness connector M50 (A) terminal 28 and M49 (B) terminal 3.
Is the inspection result normal?
YES >> GO TO 8.
NO >> GO TO 7.
7.CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connector.
3. Check continuity between A/C auto amp. harness connector M50 terminal 28 and ground.
Is the inspection result normal?
YES >> Replace A/C auto amp. Refer to VTL-7, "Removal and
Installation".
NO >> Repair or replace harness as necessary.
8.CHECK PBR REFERENCE VOLT AGE AND GROUND CIRCUITS
1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connector.
3. Check continuity between A/C auto amp. harness connector M50 (A) terminal 28 and M49 (B) terminal 3.
Is the inspection result normal?
YES >> GO TO 10.
NO >> GO TO 9.
9.CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR OPEN
1. Disconnect the defroster door motor harness connector.
2. Check continuity between defroster door motor harness connec- tor M144 (B) terminal 3, 2 and A/C auto amp. harness connector
M50 (A) terminal 28, and M49 (C) terminal 3.
Is the inspection result normal?
YES >> Replace defroster door motor. Refer to VTL-21,
"Removal and Installation".
NO >> Repair or replace harness as necessary.
10.CHECK PBR FEEDBACK VOLTAGE
Connector Te r m i n a l s
Voltage (Ap-
prox.)
(+) (-)
A/C auto amp.: M50, M49 28 35V
AWIIA0118ZZ
Continuity should not exist.
AWIIA0119ZZ
Continuity should exist.
AWIIA0120ZZ
28 - 3 : Continuity should exist.
3 - 2 : Continuity should exist.
AWIIA0121ZZ
Revision: March 2010 2008 QX56

HAC-48
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
DEFROSTER DOOR MOTOR CIRCUIT
1. Reconnect the A/C auto
amp. harness connector.
2. Turn ignition switch ON.
3. Check voltage between A/C auto amp. harness connector M49 terminal 10 and ground while cycling defroster switch on and off.
Is the inspection result normal?
YES >> GO TO 12.
NO >> GO TO 11.
11 .CHECK PBR FEEDBACK SIGNAL CIRCUIT FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect A/C auto amp. harness connector.
3. Check continuity between A/C auto amp. harness connector M49 terminal 10 and ground.
Is the inspection result normal?
YES >> Replace A/C auto amp. Refer to VTL-7, "Removal and
Installation".
NO >> Repair or replace harness as necessary.
12.CHECK PBR FEEDBACK CIRCUIT FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the defroster door motor harness connector and A/C auto amp. harness connector.
3. Check continuity between defroster door motor harness connec- tor M144 (B) terminal 4 and A/C auto amp. harness connector
M49 (A) terminal 10
Is the inspection result normal?
YES >> Replace defroster door motor. Refer to VTL-21,
"Removal and Installation".
NO >> Repair or replace harness as necessary. Voltage : Approx. 1V - 4.5V
AWIIA0157ZZ
Continuity should not exist.
AWIIA0158ZZ
Continuity should exist.
AWIIA0159ZZ
Revision: March 2010
2008 QX56

BLOWER MOTOR CONTROL SYSTEMHAC-49
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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BLOWER MOTOR CONTROL SYSTEM
System DescriptionINFOID:0000000001679795
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:• A/C auto amp.
• A/C and AV switch assembly
• Variable blower control
• Front blower motor relay
• 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 calc ulated by the A/C auto amp. 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 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 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).
AWIIA0173GB
Revision: March 2010 2008 QX56

HAC-50
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
BLOWER MOTOR CONTROL SYSTEM
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 A/C auto amp. causes the blower speed to
increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the cooling unit. The vari-
able blower control receives a gate voltage from the A/C auto amp.
to steplessly maintain the blower motor voltage in the 0 to 5 volt
range (approx.).
Front Blower Motor Co mponent Function CheckINFOID:0000000001679796
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - FRONT BLOWER
1. Push blower motor (+) switch. Blower motor should operate.
2. Push blower motor (+) switch, and continue checki ng 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 HAC-4, "
Operational Check (Front)".
Does another symptom exist?
YES >> Refer to HAC-3, "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 A/C AUTO AMP. SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to HAC-22, "
A/C Auto Amp. Self-Diagnosis".
Are any self-diagnosis codes present?
WJIA0441E
WJIA0559E
Revision: March 2010 2008 QX56

BLOWER MOTOR CONTROL SYSTEMHAC-51
< COMPONENT DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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YES >> Refer to HAC-23, "A/C System Self-Diagnosis Code Chart".
NO >> GO TO 5.
5.PERFORM A/C AND AV SWITCH ASSEMBLY SELF-DIAGNOSIS
Perform self-diagnosis to check the A/C and AV switch assembly. Refer to HAC-22, "
A/C and AV Switch
Assembly Self-Diagnosis".
Is the inspection results normal?
YES >> GO TO 6.
NO >> Replace A/C and AV switch assembly. Refer to VTL-7, "
Removal and Installation".
6.CHECK BLOWER MOTOR OPERATION
Check and verify blower motor operates manually in all speeds.
Does blower motor operate in all speeds?
YES >> GO TO 7.
NO >> Refer to HAC-51, "
Front Blower Motor Diagnosis Procedure".
7.CHECK ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT
Check engine coolant temperature sensor circuit. Refer to EC-125, "
Diagnosis Procedure".
Is the inspection results normal?
YES >> GO TO 8.
NO >> Replace engine coolant temperature sensor.
8.RECHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to HAC-4, "
Operational Check (Front)".
Does another symptom exist?
YES >> Refer to HAC-3, "How to Perform Trouble Diagnosis For Quick And Accurate Repair" .
NO >> Replace A/C auto amp. Refer to VTL-7, "
Removal and Installation".
Front Blower Motor Diagnosis ProcedureINFOID:0000000001679797
SYMPTOM: Blower motor operation is malfunctioning.
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning under starting
blower speed control.
1.CHECK FUSES
AWIIA0174GB
Revision: March 2010 2008 QX56