check engine INFINITI QX56 2008 Factory Service Manual

HIGH-PRESSURE PIPEHA-43
< ON-VEHICLE REPAIR >
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• Replace the O-rings on the rear high- and low-pr essure A/C pipes with a new ones, then apply com-
pressor oil to them for installation.
• After charging the refrigerant, check for leaks.
Removal and Installation for Underfloor Rear High- and Lo w-Pressure A/C and Heater
Core Pipes
INFOID:0000000002975449
REMOVAL
1. Drain the engine coolant. Refer to CO-11, "Changing Engine Coolant".
2. Disconnect the battery negative terminal.
3. Disconnect the generator harness.
4. Discharge the refrigerant. Refer to HA-20, "
HFC-134a (R-134a) Service Procedure".
5. Remove the front and rear bumper fascia. Refer to EXT-13, "
Removal and Installation" (front), EXT-15,
"Removal and Installation" (rear).
6. Reposition the front fender protector out of the way. Refer to EXT-23, "
Removal and Installation".
7. Disconnect the chassis harness connector.
8. Remove the spare wheel and tire.
9. Remove the tailpipe and tailpipe hanger bracket. Refer to EX-6, "
Removal and Installation".
10. Remove the seatbelt latch anchor. Refer to EX-6, "
Removal and Installation".
11. Remove the front floor heat shield.
12. Disconnect each end of the underfloor rear high- and low-pressure A/C and heater core pipes. Refer to HA-29, "
Component".
CAUTION:
Cap or wrap the joint of the pipes with suitable material such as viny l tape to avoid the entry of air.
13. Set two suitable jacks at the RH body mount points to support the vehicle body when it is separated from the RH side of the frame.
14. Remove the RH body mount bolts. Refer to BRM-2, "
Body Mounting".
15. Use the vehicle hoist to lower the RH side of the frame from the RH side of the body [approximately 305 mm (12 in)] until there is sufficient clearance to remove the underfloor rear high- and low-pressure A/C
and heater core pipes from between the body and the frame.
16. Remove the underfloor rear high- and low-pressure A/C and heater core pipes from the back of the vehi- cle.
INSTALLATION
Installation is in the reverse order of removal.
CAUTION:
• Replace the O-rings of the underfloor rear high - and low-pressure A/C and heater core pipes with
new ones, then apply compressor oil to them for installation.
• After charging refrigerant, check for leaks.
Revision: March 2010 2008 QX56

HAC-4
< BASIC INSPECTION >[AUTOMATIC AIR CONDITIONER]
INSPECTION AND ADJUSTMENT
INSPECTION AND ADJUSTMENT
Operational Check (Front)INFOID:0000000001679764
The purpose of the operational check is to
confirm that the system operates properly.
CHECKING MEMORY FUNCTION
1. Set the temperature to 32 °C (90 °F).
2. Press the OFF switch.
3. Turn ignition switch OFF.
4. Turn ignition switch ON.
5. Press the AUTO switch.
6. Confirm that the set temperature remains at previous temperature.
7. Press the OFF switch.
If NG, go to trouble diagnosis procedure for HAC-121, "
Memory Function Check".
If OK, continue with next check.
CHECKING BLOWER
1. Press the blower speed control switch (+) once, blower should operate on low speed. The fan display should have one bar lit (on display).
2. Press the blower speed control switch (+) again, and continue checking blower speed and fan display until
all speeds are checked.
3. Leave blower on maximum speed.
If NG, go to trouble diagnosis procedure for HAC-51, "
Front Blower Motor Diagnosis Procedure".
If OK, continue with next check.
CHECKING DISCHARGE AIR
1. Press MODE switch four times and the DEF switch.
2. Each position indicator should change shape (on display).
3. Confirm that discharge air comes out according to the air distribution table. Refer to HAC-15, "
Discharge
Air Flow (Front)".
Mode door position is checked in the next step.
If NG, go to trouble diagnosis procedure for HAC-26, "
Mode Door Motor (Front) Diagnosis Procedure".
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or visual inspection) and intake door position is at
fresh when the DEF or D/F is selected.
CHECKING RECIRCULATION ( , ONLY)
1. Press recirculation ( ) switch one time. Recirculation indicator should illuminate.
2. Press recirculation ( ) switch one more time. Recirculation indicator should go off.
3. Listen for intake door position change (blower sound should change slightly).
If NG, go to trouble diagnosis procedure for HAC-42, "
Intake Door Motor Diagnosis Procedure".
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or vis ual inspection) and intake door position is at fresh
when the DEF or D/F is selected. REC ( ) is not allowed in DEF ( ) D/F ( ) or FOOT ( ).
CHECKING TEMPERATURE DECREASE
1. Rotate temperature control dial (drive or passenger) counterclockwise until 18° C (60°F) is displayed.
2. Check for cold air at appropriate discharge air outlets. Conditions : Engine running and at normal operating temperature
Revision: March 2010
2008 QX56

INSPECTION AND ADJUSTMENTHAC-5
< BASIC INSPECTION > [AUTOMATIC AIR CONDITIONER]
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If NG, listen for sound of air mix door motor operat ion. If OK, go to trouble diagnosis procedure for HAC-109,
"Component Function Check". If air mix door motor appears to be malfunctioning, go to HAC-31, "Air Mix Door
Motor Component Function Check".
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockwise (drive 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 operat ion. If OK, go to trouble diagnosis procedure for HAC-117,
"Component Function Check". If air mix door motor appears to be malfunctioning, go to HAC-31, "Air Mix Door
Motor Component Function Check".
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, compre ssor clutch will already be engaged and cannot be turned off.
If NG, go to trouble diagnosis procedure for HAC-72, "
Magnet Clutch Diagnosis Procedure".
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 HAC-89, "
A/C Auto Amp Power and Ground Diagnosis Proce-
dure", then if necessary, trouble diagnosis procedure for HAC-72, "Magnet Clutch Diagnosis Procedure".
If all operational checks are OK (symptom cannot be duplicated), go to malfunction Simulation Tests in HAC-
3, "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 HAC-108, "
SymptomMatrixChart", and
perform applicable troubl e diagnosis procedures.
Operational Check (Rear)INFOID:0000000001679765
The purpose of the operational check is to confirm that the system operates properly.
CHECKING REAR BLOWER MOTOR
1. Turn the ignition switch ON.
2. Rotate rear air control (front) blower control dial to low speed.
3. Rotate the blower control dial clockwise and continue checking blower speed until all speeds are checked.
4. Leave blower on maximum speed.
5. Press the REAR CTRL switch from the rear air control (front).
6. Rotate rear air control (rear) blower control dial to low speed.
7. Rotate the blower control dial clockwise and continue checking blower speed until all speeds are checked.
8. Leave blower on maximum speed.
If NG, go to trouble diagnosis procedure for HAC-56, "
Rear Blower Motor Component Function Check".
If OK, continue with next check.
CHECKING REAR DISCHARGE AIR
Conditions : Engine running and at normal operating temperature
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.
AWIIA0182ZZ
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.
AWIIA0238ZZ
AWIIA0160GB
1 - Ground: Approx. 5V
AWIIA0161ZZ
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

HAC-114
< SYMPTOM DIAGNOSIS >[AUTOMATIC AIR CONDITIONER]
INSUFFICIENT COOLING
Trouble Diagnoses fo r Abnormal Pressure
INFOID:0000000001679834
Whenever system′s high and/or low side pressure is abnormal, diagnose using a manifold gauge. The marker
above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the stan-
dard (usual) pressure, however, differs from vehicle to vehicle, refer to above table (Ambient air temperature-
to-operating pressure table).
Both High- and Low-pressure Sides are Too High
High-pressure Side is Too High and Low-pressure Side is Too Low
High-pressure Side is Too Low and Low-pressure Side is Too High
Gauge indication Refrigerant cycleProbable causeCorrective action
Both high- and low-pressure sides
are too high. Pressure is reduced soon af-
ter water is splashed on con-
denser.
Excessive refrigerant charge in
refrigeration cycle
Reduce refrigerant until speci-
fied pressure is obtained.
Air suction by cooling fan is in-
sufficient. Insufficient condenser cooling
performance
↓
1. Condenser fins are
clogged.
2. Improper fan rotation of cooling fan • Clean condenser.
• Check and repair cooling fan
if necessary.
• Low-pressure pipe is not cold.
• When compressor is stopped high-pressure val-
ue quickly drops by approx-
imately 196 kPa (2 kg/cm
2 ,
28 psi). It then decreases
gradually thereafter. Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure decreas-
es too slowly.)
↓
Air in refrigeration cycle
Evacuate and recharge system.
Engine tends to overheat. Engine cooling systems mal-
function. Check and repair engine cool-
ing system.
• An area of the low-pressure pipe is colder than areas
near the evaporator outlet.
• Plates are sometimes cov- ered with frost. • Excessive liquid refrigerant
on low-pressure side
• Excessive refrigerant dis-
charge flow
• Expansion valve is open a lit- tle compared with the speci-
fication.
↓
Improper expansion valve ad-
justment Replace expansion valve.
AC359A
Gauge indication
Refrigerant cycleProbable causeCorrective action
High-pressure side is too high and
low-pressure side is too low. Upper side of condenser and
high-pressure side are hot,
however, liquid tank is not so
hot.High-pressure tu
be or parts lo-
cated between compressor
and condenser are clogged or
crushed. • Check and repair or replace
malfunctioning parts.
• Check oil for contamination.
AC360A
Revision: March 2010 2008 QX56