engine INFINITI QX4 2005 Factory Service Manual

ATC-124
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
PERFORMANCE CHART
Test Condition
Testing must be performed as follows:
Test Reading
Recirculating-to-discharge Air Temperature Table
Ambient Air Temperature-to-operating Pressure Table
Vehicle location Indoors or in the shade (in a well-ventilated place)
Doors Closed
Door window Open
Hood Open
TEMP. Max. COLD
Mode switch
(Ventilation) set
Recirculation (REC) switch
(Recirculation) set
Blower speedMax. speed set
Engine speed Idle speed
Operate the air conditioning system for 10 minutes before taking measurements.
Inside air (Recirculating air) at blower assembly inlet
Discharge air temperature at center ventilator
°C (°F) Relative humidity
%Air temperature
°C (°F)
50 - 6020 (68) 5.3 - 6.5 (42 - 44)
25 (77) 9.7 - 11.5 (49 - 53)
30 (86) 13.8 - 16.3 (57 - 61)
35 (95) 18.0 - 21.2 (64 - 70)
40 (104) 22.2 - 25.7 (72 - 78)
60 - 7020 (68) 6.5 - 7.7 (44 - 46)
25 (77) 11.5 - 13.3 (53 - 56)
30 (86) 16.3 - 18.8 (61 - 66)
35 (95) 21.2 - 24.0 (70 - 75)
40 (104) 25.7 - 29.2 (78 - 85)
Ambient air
High-pressure (Discharge side)
kPa (kg/cm
2 , psi)Low-pressure (Suction side)
kPa (kg/cm2 , psi) Relative humidity
%Air temperature
°C (°F)
50 - 7020 (68)680 - 840
(6.94 - 8.57, 98.6 - 121.8)160 - 198
(1.63 - 2.02, 23.2 - 28.7)
25 (77)800 - 985
(8.16 - 10.05, 116.0 - 142.8)198 - 245
(2.02 - 2.50, 28.7 - 35.5)
30 (86)940 - 1,150
(9.59 - 11.73, 136.3 - 166.8)225 - 278
(2.30 - 2.84, 32.6 - 40.3)
35 (95)1,160 - 1,410
(11.83 - 14.38, 168.2 - 204.5)273 - 335
(2.78 - 3.42, 39.6 - 48.6)
40 (104)1,325 - 1,620
(13.52 - 16.52, 192.1 - 234.9)325 - 398
(3.32 - 4.06, 47.1 - 57.7)

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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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

HEATER & COOLING UNIT ASSEMBLY
ATC-157
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Rear Heater and Cooling Unit Assembly
Removal and InstallationEJS003YF
FRONT 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. Remove the cowl top extension. Refer to EI-18, "
COWL TOP" .
4. Remove the exhaust system. Refer to EX-3, "
EXHAUST SYSTEM" .
5. Disconnect the front heater hoses from the front heater core.
6. Disconnect the high/low pressure pipes from the front expansion valve.
WJIA2000E
1. Rear heater and cooling unit assembly 2. Rear A/C pipes 3. Rear heater core pipes
4. Rear heater core hose 5. Rear blower motor 6. Underfloor rear A/C pipes
7. Underfloor rear heater core pipes

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

HEATER & COOLING UNIT ASSEMBLY
ATC-159
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3. Disconnect the rear heater core pipes.
INSTALLATION
Installation is in the reverse order of removal.
Refer to ATC-156, "
Components" .
NOTE:

Fill the engine cooling system with the specified coolant mixture. Refer to CO-11, "REFILLING ENGINE
COOLANT"

ATC-162
HEATER CORE
Revision: October 20052005 QX56
5. Remove the heater core.
NOTE:
If the in-cabin microfilters are contaminated from coolant leaking
from the heater core, replace the in-cabin microfilters with new
ones before installing the new heater core.
Installation
Installation is in the reverse order of removal.
REAR HEATER CORE
Removal
1. Partially drain the engine cooling system. Refer to MA-13, "DRAINING ENGINE COOLANT" .
2. Remove the rear RH interior trim panel. Refer to EI-35, "
BODY SIDE TRIM" .
3. Disconnect the rear heater hoses from the heater core.
4. Remove the rear heater core bracket.
5. Remove the heater core.
Installation
Installation is in the reverse order of removal.
LJIA0134E
LJIA0069E
LJIA0071E

REFRIGERANT LINES
ATC-179
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Removal and Installation for CompressorEJS003YT
A/C Compressor Mounting
REMOVAL
1. Discharge the refrigerant. Refer to ATC-175, "HFC-134a (R-134a) Service Procedure" .
2. Remove the front right wheel and tire assembly. Refer to WT-7, "
Rotation" .
3. Remove the engine under cover and the splash shield using power tool.
4. Remove the engine air cleaner and air ducts. Refer to EM-14, "
AIR CLEANER AND AIR DUCT" .
5. Remove the drive belt. Refer to EM-12, "
DRIVE BELTS" .
6. Disconnect the compressor electrical connector.
7. Disconnect the high-pressure flexible hose and low-pressure flexible hose from the compressor.
CAUTION:
Cap or wrap the joint of the pipe with suitable material such as vinyl tape to avoid the entry of air.
8. Remove the compressor bolts and nut using power tools.
WJIA0958E

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