INFINITI QX56 2004 Factory Service Manual

ATC-106
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
2. PERFORM AUTO ACTIVE TEST
Refer to PG-23, "
Auto Active Test" .
Does magnet clutch operate?
YES or NO
YES >>
WITH CONSULT-II
GO TO 5.

WITHOUT CONSULT-II
GO TO 6.
NO >> Check 10A fuse (No. 42, located in IPDM E/R), and GO TO 3.
3. CHECK CIRCUIT CONTINUITY BETWEEN IPDM E/R AND COMPRESSOR
1. Turn ignition switch OFF.
2. Disconnect IPDM E/R connector E119 and compressor (magnet
clutch) connector F3.
3. Check continuity between IPDM E/R harness connector E119
terminal 11 (Y/B) and compressor harness connector F3 termi-
nal 1 (Y/B).
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK MAGNET CLUTCH CIRCUIT
Check for operation sound when applying battery voltage direct cur-
rent to terminal.
OK or NG
OK >> Replace IPDM E/R. Refer to PG-29, "Removal and
Installation of IPDM E/R" .
NG >> Replace magnet clutch. Refer to ATC-167, "
Removal
and Installation for Compressor Clutch" .
5. CHECK BCM INPUT (COMPRESSOR ON) SIGNAL
Check compressor ON/OFF signal. Refer to AT C - 3 3 , "
CONSULT-II
Function (BCM)" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 6.
11 – 1 : Continuity should exist.
WJIA0808E
SJIA0197E
A/C SW ON : COMP ON SIG ON
A/C SW OFF : COMP ON SIG OFF
WJIA0469E

TROUBLE DIAGNOSIS
ATC-107
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AT C
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

ATC-108
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to AT C - 3 3 , "
CONSULT-II Function (BCM)" .
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-607, "
REFRIGERANT PRESSURE SENSOR" .
9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal while changing the front switch position.
Refer to ATC-33, "
CONSULT-II Function (BCM)" .
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 M18 and front air control connector
M49.
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 FAN SWITCH ON : FAN ON SIG ON
FRONT FAN SWITCH OFF : FAN ON SIG OFF
WJIA0469E
28 - 10 Continuity should exist.
WJIA0450E

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

TROUBLE DIAGNOSIS
ATC-111
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AT C
Revision: August 20072004 QX56
PERFORMANCE TEST DIAGNOSES
*1ATC-113, "PERFORMANCE
CHART"
*2AT C - 11 3 , "PERFORMANCE
CHART"
*3AT C - 11 4 , "Trouble Diagnoses for
Unusual Pressure"
*4ATC-67, "Air Mix Door Motor Circuit"
RJIA1601E

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

TROUBLE DIAGNOSIS
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

TROUBLE DIAGNOSIS
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