2008 INFINITI QX56 engine

FUNCTION INFORMATIONHAC-7
< FUNCTION DIAGNOSIS > [AUTOMATIC AIR CONDITIONER]
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FUNCTION DIAGNOSIS
FUNCTION INFORMATION
Component Part LocationINFOID:0000000001679766
ENGINE COMPARTMENT
WJIA1912E
1. Water valve F68 2. Refrigerant pressure sensor E48 3. Ambient sensor E1
4. A/C compressor F3
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

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

HAC-62
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
REAR AIR CONTROL SYSTEM
1. Start and run engine to operating temperature.
2. Turn the rear blower motor to maximum speed from the rear air control (front).
3. Turn rear air control (front) temperature control dial clockwise and then counterclockwise (REAR CTRL
indicator off).
4. Check for hot air at rear discharge air outlets in the maximum heat position and cold air at discharge air outlets in the maximum cold position.
Does the rear air control (front) operate properly?
YES >> GO TO 3.
NO >> Check rear air control (front). Refer to HAC-62, "
Air Mix Door Motor (Rear) Diagnosis Procedure".
3.CONFIRM SYMPTOM BY PERFORMING REAR AIR CO NTROL (REAR) AIR MIX DOOR MOTOR OPER-
ATIONAL CHECK
1. Press the REAR CTRL switch on rear air control (front) to send control to the rear air control (rear).
2. Turn rear air control (rear) temperature control dial slowly clockwise and then counterclockwise (REAR
CTRL indicator on).
3. Check for hot air at rear discharge air outlets in the maximum heat position and cold air at rear discharge
air outlets in the maximum cold position.
Does the rear air control (rear) operate properly?
YES >> GO TO 4.
NO >> Check rear air control (rear). Refer to HAC-58, "
Rear Air Control (Rear) Diagnosis Procedure #2".
4.CONFIRM SYMPTOM BY PERFORMING REAR AIR CONTROL (FRONT) MODE OPERATIONAL CHECK
1. Press the REAR CTRL switch on rear air control (front) (REAR CTRL indicator off).
2. Press each mode switch and check for proper air discharge at the appropriate locations.
Does the rear air control (front) operate properly?
YES >> GO TO 5.
NO >> Check mode door motor (rear). Refer to HAC-66, "
Mode Door Motor (Rear) Diagnosis Proce-
dure".
5.CONFIRM SYMPTOM BY PERFORMING REAR AIR CONTROL (REAR) MODE OPERATIONAL CHECK
1. Press the REAR CTRL switch on rear air control (f ront) to send control to the rear air control (rear).
2. Press each mode switch and check for proper air discharge at the appropriate locations.
Does the rear air control (rear) operate properly?
YES >> System OK.
NO >> Replace rear air control (rear). Refer to VTL-7, "
Removal and Installation".
Air Mix Door Motor (Rear) Diagnosis ProcedureINFOID:0000000001679806
DIAGNOSTIC PROCEDURE FOR INOPERATIVE AIR MIX DOOR MOTOR (REAR)
SYMPTOM:
• Temperature control (rear) operation is malfunctioning.
1.CHECK REAR AIR CONTROL (FRONT) POWER SUPPLY
1. Disconnect rear air control (front) harness connector.
2. Turn ignition switch ON.
3. Check voltage between rear air control (front) harness connec- tor R108 terminal 1 and ground.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair harness or connector.
2.CHECK REAR AIR CONTROL (FRONT) LIN BUS VOLTAGE
Battery voltage should exist.
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Revision: March 2010
2008 QX56

HAC-74
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
MAGNET CLUTCH
1. Reconnect BCM connector and A/C auto amp. connector.
2. Turn ignition switch ON.
3. Check voltage between A/C auto amp. harness connector M49
terminal 4 and ground.
Is the inspection result normal?
YES >> GO TO 8.
NO-1 >> If the voltage is approx. 5V when A/C switch is ON, replace A/C auto amp. Refer to VTL-7,
"Removal and Installation".
NO-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-55, "
Removal
and Installation".
8.CHECK REFRIGERANT PRESSURE SENSOR
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal 70 and ground.
Is the inspection result normal?
YES >> GO TO 9.
NO >> Refer to EC-423, "
Diagnosis Procedure".
9.CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to HAC-20, "
CONSULT-III Function (HVAC)".
Is the inspection result normal?
YES >> GO TO 12.
NO >> GO TO 10.
10.CHECK CIRCUIT CONTINUITY BETW EEN BCM AND A/C AUTO AMP.
Te r m i n a l s
Condition Voltage
(+)
(-)
A/C auto
amp. con-
nector Te r m i n a l N o .
M49 4 Ground A/C switch: ON Approx. 0V
A/C switch: OFF Approx. 5V
AWIIA0200ZZ
Te r m i n a l s
ConditionVoltage
(+)
(-)
ECM con-
nector Te r m i n a l N o .
F54 70 Ground A/C switch: ON Approx. 0.36 - 3.88V
LJIA0124E
FRONT BLOWER CONTROL
DIAL ON : FAN ON SIG ON
FRONT BLOWER CONTROL
DIAL OFF : FAN ON SIG OFF
Revision: March 2010
2008 QX56

HAC-76
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
WATER VALVE CIRCUIT
WATER VALVE CIRCUIT
DescriptionINFOID:0000000001679811
COMPONENT DESCRIPTION
Water Valve
The water valve (1) cuts the flow of engine coolant to the front and
rear heater cores to allow for maximum cooling during A/C opera-
tion. It is controlled by the A/C auto amp.
Water Valve Diagnosis ProcedureINFOID:0000000001679812
DIAGNOSTIC PROCEDURE FOR WATER VALVE
1.CHECK WATER VALVE POWER AND GROUND CIRCUITS
1. Disconnect water valve connector F68.
2. Turn ignition switch ON.
3. Rotate temperature control dial (driver) to 32 °C (90° F).
4. Check voltage between water valve harness connector F68 ter- minal 1 and terminal 2 while rotating temperature control dial
(driver) to 18 °C (60° F).
Is the inspection result normal?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect A/C auto amp. connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 2 and A/C auto amp. harness connector M50 (B)
terminal 46.
4. Check continuity between water valve harness connector F68 (A) terminal 2 and ground.
Is the inspection result normal?
YES >> Replace A/C auto amp. Refer to VTL-7, "Removal and Installation".
NO >> Repair harness or connector.
3.CHECK WATER VALVE POWER AND GROUND CIRCUITS
WJIA1791E
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 2 1Rotate temperature
control dial Battery
voltage
WJIA1794E
2 - 46 : Continuity should exist.
2 - Ground : Continuity should not exist.
AWIIA0203ZZ
Revision: March 2010 2008 QX56

HAC-78
< COMPONENT DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
AMBIENT SENSOR
AMBIENT SENSOR
Component DescriptionINFOID:0000000001679813
COMPONENT DESCRIPTION
Ambient Sensor
The ambient sensor (1) 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 A/C auto amp.
AMBIENT TEMPERATURE INPUT PROCESS
The A/C auto amp. includes a processing circuit for the
ambient sensor input. However, when the temperature
detected by the ambient sensor increas es quickly, the processing circuit retards the A/C auto amp. function. It
only allows the A/C auto amp. to recognize an ambient temperature increase of 0.33°C (0.6°F) per 100 sec-
onds.
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 co mpartment can radiate to the front grille area, loca-
tion of the ambient sensor.
Ambient Sensor Diagnosis ProcedureINFOID:0000000001679814
DIAGNOSTIC PROCEDURE FOR AMBIENT SENSOR
SYMPTOM: Ambient sensor circuit is open or shorted. (40 or 41 is
indicated on A/C auto amp. as a result of conducting the A/C auto
amp. self-diagnosis)
1.CHECK VOLTAGE BETWEEN AM BIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1 terminal 1 and ground.
Is the inspection result normal?
YES >> GO TO 2.
NO >> GO TO 4.
2.CHECK CIRCUIT CONTINUITY BETWEEN AM BIENT SENSOR AND A/C AUTO AMP.
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1 - Ground: Approx. 5V
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Revision: March 2010 2008 QX56

HAC-110
< SYMPTOM DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
INSUFFICIENT COOLING
NO >> Check water valve circuit. Refer to
HAC-76, "Water Valve Diagnosis Procedure".
9.CHECK RECOVERY/RECYCLING EQUIPMENT BEFORE USAGE
Check recovery/recycling equipment before connecting to vehicle. Verify there is no pressure in the recovery/
recycling equipment by checking the gauges. If pressure exists, recover refrigerant from equipment lines.
>> GO TO 10.
10.CHECK REFRIGERANT PURITY
1. Connect recovery/recycling equipment to vehicle.
2. Confirm refrigerant purity in supply tank us ing recovery/recycling and refrigerant identifier.
Is the inspection result normal?
YES >> GO TO 11.
NO >> Check contaminated refrigerant. Refer to HAC-122, "
Working with HFC-134a (R-134a)".
11 .CHECK FOR EVAPORATOR FREEZE UP
Start engine and run A/C. Check for evaporator freeze up.
Does evaporator freeze up?
YES >> Perform diagnostic work flow. Refer to HAC-110, "Diagnostic Work Flow".
NO >> GO TO 12.
12.CHECK REFRIGERANT PRESSURE
Check refrigerant pressure with manifold gauge connected. Refer to HAC-113, "
Performance Chart".
Is the inspection result normal?
YES >> Perform diagnostic work flow. Refer to HAC-110, "Diagnostic Work Flow".
NO >> GO TO 13.
13.CHECK AIR DUCTS
Check ducts for air leaks.
Is the inspection result normal?
YES >> System OK.
NO >> Repair air leaks.
Diagnostic Work FlowINFOID:0000000001679831
Revision: March 2010 2008 QX56