Ins INFINITI QX56 2004 Factory Service Manual

TROUBLE DIAGNOSIS
ATC-107
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Revision: August 20072004 QX56
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector M18 and front air control connector
M49.
3. Check continuity between BCM harness connector M18 terminal
27 (W/R) and front air control harness connector M49 terminal
12 (W/R).
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VOLTAGE FOR FRONT AIR CONTROL (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 (W/R) 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-135,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-19, "
Removal
and Installation of BCM" . 27 - 12 Continuity should exist.
WJIA0809E
Te r m i n a l s
ConditionVoltag e
(Approx.) (+)
(-) Front air
control con-
nectorTe r m i n a l N o .
(Wire color)
M49 12 (W/R) GroundA/C switch: ON 0V
A/C switch: OFF 5V
WJIA0449E

TROUBLE DIAGNOSIS
ATC-109
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Revision: August 20072004 QX56
11 . CHECK VOLTAGE FOR FRONT AIR CONTROL (FAN 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 10 (L/R) and ground.
OK or NG
OK >> Check CAN communication. Refer to ATC-32, "CAN Communication System Description" .
NG-1 >> If the voltage is approx. 5V when blower motor is ON, replace front air control. Refer to ATC-135,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when blower motor is OFF, replace BCM. Refer to BCS-19, "
Removal
and Installation of BCM" .
Te r m i n a l s
ConditionVo ltag e
(Approx.) (+)
(-)
Front air con-
trol connectorTe r m i n a l N o .
(Wire color)
M49 10 (L/R) GroundA/C switch: ON
Blower motor
operates0V
A/C switch: OFF 5V
WJIA0451E

ATC-110
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Insufficient CoolingEJS002CM
SYMPTOM: Insufficient cooling
INSPECTION FLOW
*1 .AT C - 5 6 , "Operational Check
(Front)"
*2AT C - 5 3 , "A/C System Self-diagno-
sis Function"
*3AT C - 5 5 , "SELF-DIAGNOSIS CODE
CHART"
*4 EC-410, "SYSTEM DESCRIPTION"*5AT C - 5 , "Contaminated Refrigerant"*6 .AT C - 111 , "PERFORMANCE TEST
DIAGNOSES"
*7ATC-113, "Test Reading"*8MA-12, "Checking Drive Belts"*9ATC-121, "Water Valve Circuit"
WJIA0963E

ATC-112
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
*1ATC-167, "Removal and Installation
for Compressor Clutch"
*2ATC-83, "Front Blower Motor Circuit"*3MA-12, "Checking Drive Belts"
WJIA0361E

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ATC-113
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Revision: August 20072004 QX56
PERFORMANCE CHART
Test Condition
Testing must be performed as follows:
Te s t R e a d i n g
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
Fan (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)

ATC-114
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
TROUBLE DIAGNOSES FOR UNUSUAL PRESSURE
Whenever system′s high and/or low side pressure(s) is/are unusual, diagnose using a manifold gauge. The
marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the
standard (usual) pressure, however, differs from vehicle to vehicle, refer to preceding table (Ambient air tem-
perature-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
as 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

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ATC-115
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Revision: August 20072004 QX56
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
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
between high- and low-pres-
sure sides.Compressor pressure opera-
tion is improper.
↓
Damaged inside compressor
packings.Replace compressor.
AC356A
Gauge indication Refrigerant cycle Probable cause Corrective action
Both high- and low-pressure sides
are too low.

There is a big temperature
difference between receiver
drier outlet and inlet. Outlet
temperature is extremely
low.

Liquid tank inlet and expan-
sion valve are frosted.Liquid tank inside is slightly
clogged.

Replace liquid tank.

Check lubricant for contami-
nation.

Temperature of expansion
valve inlet is extremely low
as compared with areas
near liquid tank.

Expansion valve inlet may
be frosted.

Temperature difference
occurs somewhere in high-
pressure side.High-pressure pipe located
between receiver drier and
expansion valve is clogged.

Check and repair malfunc-
tioning parts.

Check lubricant for contami-
nation.
Expansion valve and liquid
tank are warm or only cool
when touched.Low refrigerant charge.
↓
Leaking fittings or compo-
nents.Check refrigerant system for
leaks. Refer to ATC-178,
"Checking for Refrigerant
Leaks" .
There is a big temperature dif-
ference between expansion
valve inlet and outlet while the
valve itself is frosted.Expansion valve closes a little
compared with the specifica-
tion.
↓
1. Improper expansion valve
adjustment.
2. Malfunctioning expansion
valve.
3. Outlet and inlet may be
clogged.

Remove foreign particles by
using compressed air.

Check lubricant for contami-
nation.
An area of the low-pressure
pipe is colder than areas near
the evaporator outlet.Low-pressure pipe is clogged
or crushed.

Check and repair malfunc-
tioning parts.

Check lubricant for contami-
nation.
Air flow volume is too low. Evaporator is frozen.

Check intake sensor circuit.
Refer to ATC-133, "
Intake
Sensor Circuit" .

Replace compressor.
AC353A

TROUBLE DIAGNOSIS
ATC-117
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Revision: August 20072004 QX56
Insufficient HeatingEJS002CN
SYMPTOM: Insufficient heating
INSPECTION FLOW
*1 .ATC-56, "Operational Check
(Front)" or AT C - 5 9 , "Operational
Check (Rear)"
*2AT C - 6 7 , "Air Mix Door Motor Circuit"*3AT C - 5 3 , "A/C System Self-diagno-
sis Function"
*4AT C - 5 3 , "A/C System Self-diagnosis
Function"
*5AT C - 8 3 , "Front Blower Motor Circuit"*6EC-165, "DTC P0117, P0118 ECT
SENSOR"
*7MA-12, "Changing Engine Coolant"*8CO-8, "CHECKING RESERVOIR
CAP"
*9ATC-121, "Water Valve Circuit"
*10CO-4, "OVERHEATING CAUSE
ANALYSIS"
WJIA0812E

ATC-118
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
NoiseEJS002CO
SYMPTOM: Noise
INSPECTION FLOW
WJIA0473E

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ATC-119
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Revision: August 20072004 QX56
*1ATC-167, "REMOVAL"*2ATC-168, "INSTALLATION"*3AT C - 2 2 , "Maintenance of Lubricant
Quantity in Compressor"
*4ATC-56, "Operational Check (Front)"
or AT C - 5 9 , "
Operational Check
(Rear)"
*5MA-12, "Checking Drive Belts"