check engine INFINITI QX4 2005 Factory Service Manual

ATC-60
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Operational Check (Rear)EJS003XM
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear blower control dial to switch position "1". Blower
should operate on low speed.
2. Turn the rear blower control dial counterclockwise to switch
position "2", "3", and "4" until all speeds are checked.
3. Leave blower on MAX speed.
If NG, go to trouble diagnosis procedure for ATC-101, "
Rear Blower
Motor Circuit" .
If OK, continue the check.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature and mode dial fully counterclockwise.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation if OK, go to
trouble diagnosis procedure for ATC-121, "
Insufficient Cooling" . If
air mix door motor appears to be malfunctioning, go to ATC-79,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature and mode dial clockwise.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-128, "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to ATC-79,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue the check.Conditions : Engine running and at normal operating temperature
WJIA1350E
WJIA1069E
WJIA1070E

TROUBLE DIAGNOSIS
ATC-119
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8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to ATC-33, "
CONSULT-II Function (HVAC)" .
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal
70 (B/W) and ground.
OK or NG
OK >>
WITH CONSULT-II
GO TO 9.

WITHOUT CONSULT-II
GO TO 10.
NG >> Refer to EC-643, "
REFRIGERANT PRESSURE SENSOR" .
9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to ATC-33, "
CONSULT-II Function
(HVAC)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal
28 (L/R) and front air control harness connector M49 terminal 10
(L/R).
OK or NG
OK >> GO TO 11.
NG >> Repair harness or connector.
Te r m i n a l s
Condition Voltage (+)
(-)
ECM con-
nectorTe r m i n a l N o .
(Wire color)
F54 70 (B/W) 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
28 - 10 Continuity should exist.
WJIA0450E

TROUBLE DIAGNOSIS
ATC-125
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TROUBLE DIAGNOSES FOR UNUSUAL PRESSURE
Whenever system′s high and/or low side pressure is unusual, 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
Gauge indication Refrigerant cycle Probable cause Corrective action
Both high- and low-pressure sides
are too high.Pressure is reduced soon
after water is splashed on
condenser.Excessive refrigerant charge
in refrigeration cycleReduce refrigerant until speci-
fied pressure is obtained.
Air suction by cooling fan is
insufficient.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
value quickly drops by
approximately 196 kPa (2
kg/cm
2 , 28 psi). It then
decreases gradually there-
after.Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure
decreases too slowly.)
↓
Air in refrigeration cycleEvacuate and recharge sys-
tem.
Engine tends to overheat.Engine cooling systems mal-
function.Check and repair engine cool-
ing system.

An area of the low-pres-
sure 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
little compared with the
specification.
↓
Improper expansion valve
adjustmentReplace 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 tube or parts
located between compressor
and condenser are clogged or
crushed.

Check and repair or replace
malfunctioning parts.

Check lubricant for contami-
nation.
AC360A

TROUBLE DIAGNOSIS
ATC-133
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Revision: October 20052005 QX56
Memory FunctionEJS003Y0
SYMPTOM: Memory function does not operate.
INSPECTION FLOW
Water Valve CircuitEJS003Y1
COMPONENT DESCRIPTION
Water Valve
The water valve cuts the flow of engine coolant to the front and rear
heater cores to allow for maximum cooling during A/C operation. It is
controlled by the front air control through the water valve relay.
*1ATC-61, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 7 , "Operational Check (Front)"*3AT C - 5 5 , "A/C System Self-diagnosis
Function"
*4ATC-56, "SELF-DIAGNOSIS CODE
CHART"
WJIA1287E
WJIA1015E

TROUBLE DIAGNOSIS
ATC-137
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Revision: October 20052005 QX56
Ambient Sensor CircuitEJS003Y2
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, the 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 compartment can radiate to the front grille area, loca-
tion of the ambient sensor.
DIAGNOSTIC PROCEDURE FOR AMBIENT SENSOR
SYMPTOM: Ambient sensor circuit is open or shorted. Using the
CONSULT-II, DTC B257B or B257C is displayed. Without a CON-
SULT-II, code 40 or 41 is indicated on front air control as a result of
conducting the front air control self-diagnosis.
1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1
terminal 1 (P) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
WJIA0562E
WJIA0456E
1 - Ground : Approx. 5V
WJIA1971E

ATC-158
HEATER & COOLING UNIT ASSEMBLY
Revision: October 20052005 QX56
7. Move the two front seats to the rearmost position on the seat track.
8. Remove the instrument panel and console panel. Refer to IP-10, "
INSTRUMENT PANEL ASSEMBLY" .
9. Remove the steering column. Refer to PS-10, "
STEERING COLUMN" .
10. Disconnect the instrument panel wire harness at the RH and LH in-line connector brackets, and the fuse
block (J/B) electrical connectors. Refer to PG-4, "
POWER SUPPLY ROUTING CIRCUIT" .
11. Disconnect the steering member from each side of the vehicle body.
12. Remove the front heater and cooling unit assembly with it attached to the steering member, from the vehi-
cle.
CAUTION:
Use care not to damage the seats and interior trim panels when removing the front heater and
cooling unit assembly with it attached to the steering member.
13. Remove the front heater and cooling unit assembly from the steering member.
Installation
Installation is in the reverse order of removal.
CAUTION:

Replace the O-ring of the low-pressure pipe and high-pressure pipe with a new one, and apply
compressor oil to it when installing it.

After charging the refrigerant, check for leaks.
NOTE:

Fill the engine cooling system with the specified coolant mixture. Refer to MA-14, "REFILLING ENGINE
COOLANT" .

Recharge the A/C system. Refer to ATC-175, "Evacuating System and Charging Refrigerant" .
REAR HEATER AND COOLING UNIT ASSEMBLY
Removal
1. Discharge the refrigerant from the A/C system. Refer to ATC-175, "Discharging Refrigerant" .
2. Drain the coolant from the engine cooling system. Refer to MA-13, "
DRAINING ENGINE COOLANT" .
3. Disconnect the rear heater core hoses from the rear heater core.
4. Disconnect the rear A/C pipes from the rear expansion valve.
5. Remove the rear RH interior trim panel. Refer to EI-35, "
BODY
SIDE TRIM" .
6. Disconnect the following electrical connectors:

Rear blower motor

Rear blower motor resistor

Rear air mix door motor
7. Disconnect the ducts from the rear heater and cooling unit
assembly.
8. Remove the rear heater and cooling unit assembly.
Installation
Installation is in the reverse order of removal.
CAUTION:

Replace the O-ring of the low-pressure pipe and high-pressure pipe with a new one, and apply
compressor oil to it when installing it.

After charging the refrigerant, check for leaks.
NOTE:

Fill the engine cooling system with the specified coolant mixture. Refer to MA-14, "REFILLING ENGINE
COOLANT" .

Recharge the A/C system. Refer to ATC-175, "Evacuating System and Charging Refrigerant" .
Removal and Installation for Rear Heater Core PipesEJS00536
REMOVAL
1. Drain the coolant from the engine cooling system. Refer to CO-10, "DRAINING ENGINE COOLANT" .
2. Remove the upper and lower luggage RH side finisher. Refer to EI-35, "
BODY SIDE TRIM"
LJIA0021E

ATC-182
REFRIGERANT LINES
Revision: October 20052005 QX56
2. Install the magnet coil harness clip using a screwdriver.
3. Install the pulley assembly using Tool and a wrench, then install
the snap ring using snap ring pliers.
4. Install the clutch disc on the compressor shaft, together with the
original shim(s). Press the clutch disc down by hand.
5. Install the clutch pulley bolt using Tool, to prevent the clutch disc
from turning and tighten the bolt to specification.
CAUTION:
After tightening the clutch pulley bolt, check that the clutch
pulley rotates smoothly.
6. Check the pulley clearance all the way around the clutch disc as
shown.
7. If the specified clearance is not obtained, replace the adjusting
spacer to readjust.
8. Connect the compressor electrical connector.
9. Install the drive belt. Refer to EM-12, "
DRIVE BELTS" .
10. Install the engine under cover and the splash shield.Tool number : — (J-38873-A)
WJIA1016E
WHA184
Tool number : J-44614
WHA229
Clutch disc-to-pulley clearance : 0.3 - 0.6 mm
(0.012 - 0.024 in)
WHA194

REFRIGERANT LINES
ATC-183
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Revision: October 20052005 QX56
BREAK-IN OPERATION
When replacing compressor clutch assembly, always conduct the break-in operation. This is done by engag-
ing and disengaging the clutch about 30 times. Break-in operation raises the level of transmitted torque.
Removal and Installation for Low-pressure Flexible HoseEJS003YV
REMOVAL
1. Remove the engine room cover using power tools.
2. Remove the engine air cleaner and air ducts. Refer to EM-14, "
AIR CLEANER AND AIR DUCT"
3. Remove the cowl top extension. Refer to EI-18, "COWL TOP" .
4. Discharge the refrigerant. Refer to ATC-175, "
HFC-134a (R-134a) Service Procedure" .
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of air.
5. Remove the low-pressure flexible hose.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .
CAUTION:

Replace the O-ring of the low-pressure flexible hose with a new one, then apply compressor oil to
it when installing it.

After charging refrigerant, check for leaks.
Removal and Installation for High-pressure Flexible HoseEJS003YW
REMOVAL
1. Remove the engine under cover.
2. Remove the engine air cleaner and air ducts. Refer to EM-14, "
AIR CLEANER AND AIR DUCT" .
3. Discharge the refrigerant. Refer to ATC-175, "
HFC-134a (R-134a) Service Procedure" .
4. Remove the high-pressure flexible hose.
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of air.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .
CAUTION:

Replace the O-ring of the high-pressure flexible hose with a new one, then apply compressor oil to
it when installing it.

After charging refrigerant, check for leaks.
Removal and Installation for High-pressure PipeEJS003YX
REMOVAL
1. Remove the cowl top extension. Refer to EI-18, "COWL TOP" .
2. Disconnect the battery negative cable.
3. Reposition the IPDM E/R aside.
4. Remove the front right wheel and tire assembly. Refer to WT-7, "
Rotation" .
5. Position aside the front floor insulator.
6. Discharge the refrigerant. Refer to ATC-175, "
HFC-134a (R-134a) Service Procedure" .
7. Remove the low pressure pipe. Refer to ATC-184, "
Removal and Installation for Low-pressure Pipe" .
8. Remove the high-pressure pipe.
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of air.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .

ATC-184
REFRIGERANT LINES
Revision: October 20052005 QX56
CAUTION:

Replace the O-ring of the high-pressure pipe with a new one, then apply compressor oil to it when
installing it.

After charging refrigerant, check for leaks.
Removal and Installation for Low-pressure PipeEJS003YY
REMOVAL
1. Discharge the refrigerant. Refer to ATC-175, "HFC-134a (R-134a) Service Procedure" .
2. Remove the cowl top and the cowl top extension. Refer to EI-18, "
COWL TOP" .
3. Remove the low-pressure pipe.
CAUTION:
Cap or wrap the joint of the pipes with suitable material such as vinyl tape to avoid the entry of air.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .
CAUTION:

Replace the O-ring of the high/low-pressure pipe with a new one, then apply compressor oil to it
when installing it.

After charging refrigerant, check for leaks.
Removal and Installation for Underfloor Rear A/C PipesEJS00537
REMOVAL
1. Drain the coolant from the engine cooling system. Refer to CO-10, "DRAINING ENGINE COOLANT" .
2. Diconnect the negative battery terminal.
3. Discharge the refrigerant from the A/C system. Refer to ATC-175, "
HFC-134a (R-134a) Service Proce-
dure" .
4. Disconnect the chassis harness connector.
5. Set four suitable jacks at the body mounting points to support the vehicle body when it is seperated from
the frame.
6. Remove the RH body mount bolts. Refer to BL-159, "
Body Mounting"
7. Use the vehicle hoist to lower the frame from the body until there is sufficient clearance for the underfloor
rear high- and low-pressure A/C and heater core pipes from the body.
8. Remove the underfloor rear high- and low-pressure A/C and heater core pipes .
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .
CAUTION:

Replace the O-rings of the high-pressure pipe and the high-pressure flexible hose with new ones,
then apply compressor oil to them after installing them.

After charging refrigerant, check for leaks.
Removal and Installation for Rear A/C PipesEJS00538
REMOVAL
1. Discharge the refrigerant from the A/C system. Refer to ATC-175, "HFC-134a (R-134a) Service Proce-
dure"
2. Remove the upper and lower luggage RH side finisher lower. Refer to EI-35, "BODY SIDE TRIM"
3. Disconnect the rear A/C pipes.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-177, "
Components" .
CAUTION:

Replace the O-rings of the high-pressure pipe and the high-pressure flexible hose with new ones,
then apply compressor oil to them after installing them.

After charging refrigerant, check for leaks.

ATC-190
REFRIGERANT LINES
Revision: October 20052005 QX56
2. Pour one bottle 7.4 cc (1/4 ounce) of the HFC-134a (R-134a) fluorescent leak detection dye (J-41447) into
the HFC-134a (R-134a) dye injector (J-41459).
CAUTION:
If repairing the A/C system or replacing a component, pour the HFC-134a (R-134a) fluorescent leak
detection dye (J-41447) directly into the open system connection and proceed with the service
procedures.
3. Connect the refrigerant dye injector (J-41459) to the low-pressure service valve.
4. Start the engine and switch the A/C system ON.
5. When the A/C system is operating (compressor running), inject one bottle 7.4 cc (1/4 ounce) of HFC-134a
(R-134a) fluorescent leak detection dye (J-41447) through the low-pressure service valve using HFC-
134a (R-134a) dye injector (J-41459). Refer to the manufacturer's operating instructions.
6. With the engine still running, disconnect the HFC-134a (R-134a) dye injector (J-41459) from the low-pres-
sure service valve.
7. Operate the A/C system for a minimum of 20 minutes to mix the HFC-134a (R-134a) fluorescent leak
detection dye (J-41447) with the A/C system oil. Depending on the leak size, operating conditions and
location of the leak, it may take from minutes to days for the HFC-134a (R-134a) fluorescent leak detec-
tion dye to penetrate an A/C system leak and become visible.
Electronic Refrigerant Leak DetectorEJS003Z8
PRECAUTIONS FOR HANDLING LEAK DETECTOR
NOTE:
When performing a refrigerant leak check, use a electronic refrigerant leak detector (J-41995) or equivalent.
Ensure that the electronic refrigerant leak detector (J-41995) is calibrated and set properly according to the
manufacturer's operating instructions.
The electronic refrigerant leak detector (J-41995) is a delicate
device. To use the leak detector properly, read the manufacturer's
operating instructions and perform any specified maintenance.
1. Position the probe approximately 5 mm (3/16 in) away from the
point to be checked as shown.
SHA1 96 FA
SHA707EA