2007 INFINITI QX56 check engine

TROUBLE DIAGNOSISATC-85
< SERVICE INFORMATION >
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Check continuity between terminals by supplying 12 volts and
ground to coil side terminals of relay.
Front Blower Motor
Confirm smooth rotation of the blower motor.
• Ensure that there are no foreign particles inside the blower unit.
• Apply 12 volts to terminal 2 and ground to terminal 1 and verify that the motor operates freely and quietly.
Rear Blower Motor CircuitINFOID:0000000003533257
SYMPTOM:
• Blower motor operation is malfunctioning.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIO NAL CHECK - REAR AIR CONTROL (FRONT)
1. Press AUTO switch.
2. Set the rear blower control dial (front) to REAR position.
3. Turn the rear blower control dial (rear) and check for rear blower operation. NOTE:
If the engine coolant temperature increases above 111.9 °C (233.6 °F) the front air control turns OFF the
rear blower motor. When the engine coolant temperature drops below 110 °C (230 °F) the front air control
turns the rear blower motor back ON.
4. Continue checking that rear blower speed increases as the rear blower control dial is rotated clockwise.
Does the rear blower motor operate correctly?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK FOR ANY SYMPTOMS
WJIA1401E
WJIA1508E

TROUBLE DIAGNOSISATC-99
< SERVICE INFORMATION >
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7.CHECK VOLTAGE FOR FRONT AIR CO NTROL (COMPRESSOR ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 12 and ground.
OK or NG
OK >> GO TO 8.
NG-1 >> If the voltage is approx. 5V when A/C switch is ON, replace front air control. Refer to ATC-123,
"Removal and Installation".
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-24, "
BCM".
8.CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to EC-638
.
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal
70 and ground.
OK or NG
OK >> • WITH CONSULT-II GO TO 9.
• WITHOUT CONSULT-II GO TO 10.
NG >> Refer to EC-638
.
9.CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to ATC-30, "
CONSULT-II Function
(HVAC)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10.CHECK CIRCUIT CONTINUITY BETWEE N BCM AND FRONT AIR CONTROL
Te r m i n a l s
Condition Voltage
(+)
(-)
Front air con-
trol connec- tor Te r m i n a l N o .
M49 12 Ground A/C switch: ON Approx. 0V
A/C switch: OFF Approx. 5V
WJIA0449E
Te r m i n a l s
Condition Voltage
(+)
(-)
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
WJIA0469E

TROUBLE DIAGNOSISATC-101
< SERVICE INFORMATION >
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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 3.
4.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
OK or NG
OK >> GO TO 5.
NG >> Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
5.CHECK DRIVE BELTS
Check compressor belt tension. Refer to EM-13, "
Checking Drive Belts" .
OK or NG
OK >> GO TO 6.
NG >> Adjust or replace compressor belt. Refer to EM-13, "
Removal and Installation" .
6.CHECK AIR MIX DOOR OPERATION
Check and verify air mix door me chanism for smooth operation.
Does air mix door operate correctly?
YES >> GO TO 7.
NO >> Repair or replace air mix door control linkage.
7.CHECK COOLING FAN MOTOR OPERATION
Check and verify cooling fan moto r for smooth operation. Refer to EC-469, "
Description" .
Does cooling fan motor operate correctly?
YES >> GO TO 8.
NO >> Check cooling fan motor. Refer to EC-469
.
8.CHECK WATER VALVE OPERATION
Check and verify water valve for smooth operation. Refer to ATC-113, "
Water Valve Circuit".
Does water valve operate correctly?
YES >> GO TO 8.
NO >> Check water valve circuit. Refer to ATC-113, "
Water Valve Circuit" .
9.CHECK RECOVERY/RECYCLING EQUIPMENT BEFORE USAGE
Check recovery/recycling equipment befor e 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 9.
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.
OK or NG
OK >> GO TO 10.
NG >> Check contaminated refrigerant. Refer to AT C - 3 , "
Contaminated Refrigerant" .
11 .CHECK FOR EVAPORATOR FREEZE UP
Start engine and run A/C. Check for evaporator freeze up.
Does evaporator freeze up?
YES >> Perform performance test diagnoses. Refer to "PERFORMANCE TEST DIAGNOSES" .
NO >> GO TO 11.

ATC-106
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
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
Both High- and Low-pressure Sides are Too Low
Gauge indication Refrigerant cycle Probable cause Corrective 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 cycle Probable cause Corrective 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
Gauge indication Refrigerant cycle Probable cause Corrective action
High-pressure side is too low and
low-pressure side is too high. High- and low-pressure sides
become equal soon after com-
pressor operation stops.Compressor pressure opera-
tion is improper.
↓
Damaged inside compressor
packings.
Replace compressor.
No temperature difference be-
tween high- and low-pressure
sides. Compressor pressure opera-
tion is improper.
↓
Damaged inside compressor
packings.
Replace compressor.
AC356A

ATC-108
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Insufficient Heating
INFOID:0000000003533261
SYMPTOM: Insufficient heating
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPER ATIONAL CHECK - TEMPERATURE INCREASE
1. Press the AUTO switch.
2. Turn the temperature control dial (driver) clockwise until 32 ° C (90 ° F) is displayed.
3. Check for hot air at discharge air outlets.
Can this symptom be duplicated?
YES >> GO TO 2.
NO >> Perform complete system operational check. Refer to ATC-50, "
Operational Check (Front)" .
2.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 3.
3.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
OK or NG
OK >> GO TO 4.
NG >> Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
4.CHECK ENGINE COOLING SYSTEM
1. Check for proper engine coolant level. Refer to CO-9, "
Inspection".
2. Check hoses for leaks or kinks.
3. Check radiator cap. Refer to CO-9, "
Inspection" .
4. Check for air in cooling system.
>> GO TO 5.
5.CHECK AIR MIX DOOR OPERATION
Check the operation of the air mix door.
OK or NG
Gauge indication Refrigerant cycle Probable cause Corrective action
Low-pressure side becomes nega-
tive. Liquid tank or front/rear side of
expansion valve′s pipe is frost-
ed or dewed. High-pressure side is closed
and refrigerant does not flow.
↓
Expansion valve or liquid tank
is frosted. Leave the system at rest until
no frost is present. Start it
again to check whether or not
the malfunction is caused by
water or foreign particles.
• If water is the cause, initially
cooling is okay. Then the wa-
ter freezes causing a block-
age. Drain water from
refrigerant or replace refrig-
erant.
• If due to foreign particles, re-
move expansion valve and
remove the particles with dry
and compressed air (not
shop air).
• If either of the above meth- ods cannot correct the mal-
function, replace expansion
valve.
• Replace liquid tank.
• Check oil for contamination.
AC362A

TROUBLE DIAGNOSISATC-109
< SERVICE INFORMATION >
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OK >> GO TO 6.
NG >> Check the air mix door motor circuit. Refer to ATC-59, "
Air Mix Door Motor Circuit" .
6.CHECK AIR DUCTS
Check for disconnected or leaking air ducts.
OK or NG
OK >> GO TO 7.
NG >> Repair all disconnected or leaking air ducts.
7.CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses.
OK or NG
OK >> Hot inlet hose and a warm outlet hose: GO TO 8.
NG >> • Inlet hose cold: GO TO 11. • Both hoses warm: GO TO 9.
8.CHECK ENGINE COOLANT SYSTEM
Check engine control temperature sensor. Refer to EC-205
.
OK or NG
OK >> System OK.
NG >> Repair or replace as necessary. Retest.
9.CHECK HEATER HOSES
Check heater hoses for proper installation.
OK or NG
OK >> System OK.
NG >> 1. Back flush heater core. 2. Drain the water from the system.
3. Refill system with new engine coolant. Refer to CO-9, "
Changing Engine Coolant" .
4. GO TO 10 to retest.
10.CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses.
OK or NG
OK >> System OK.
NG >> Replace heater core. Refer to ATC-135
.
11 .CHECK WATER VALVE
Check the operation of the water valve. Refer to ATC-113, "
Water Valve Circuit".
OK or NG
OK >> System OK.
NG >> Replace water valve.
NoiseINFOID:0000000003533262
SYMPTOM: Noise
INSPECTION FLOW

TROUBLE DIAGNOSISATC-113
< SERVICE INFORMATION >
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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".
Water Valve CircuitINFOID:0000000003533265
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 front air control.
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 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2.CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 1 and front air control harness connector M50 (B)
terminal 29.
4. Check continuity between water valve harness connector F68 (A) terminal 1 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal and Installation".
WJIA1791E
ConnectorTe r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 1 2 Rotate temperature
control dial Battery
voltage
WJIA1792E
1 - 29 : Continuity should exist.
1 - Ground : Continuity should not exist.
WJIA1793E

ATC-114
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
NG >> Repair harness or connector.
3.CHECK WATER VALVE POWER AND GROUND CIRCUITS
1. Rotate temperature control dial (driver) to 16 °C (60 °F).
2. Check voltage between water valve harness connector F68 ter- minal 1 and terminal 2 while rotating temperature control dial
(driver) to 32 °C (90 °F).
OK or NG
OK >> Replace the water valve.
NG >> GO TO 4.
4.CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 2 and front air control harness connector M50 (B)
terminal 30.
4. Check continuity between water valve harness connector F68 (A) terminal 2 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal and Installation" .
NG >> Repair harness or connector.
Ambient Sensor CircuitINFOID:0000000003533266
COMPONENT DESCRIPTION
Ambient Sensor
The ambient sensor 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 front air control.
AMBIENT TEMPERATURE INPUT PROCESS
The front air control includes a processing circuit for the ambient sensor input. However, when the tempera-
ture detected by the ambient sensor increases quickly, t he processing circuit retards the front air control func-
tion. It only allows the front air control to recognize an ambient temperature increase of 0.33 °C (0.6 °F) per 100
seconds.
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.
Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 2 1 Rotate temperature
control dial Battery
voltage
WJIA1794E
2 - 30 : Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA1796E
WJIA0819E