2004 INFINITI QX56 Factory Service Manual

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Page 513 of 3371

INFINITI QX56 2004 Factory Service Manual 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 , "

Page 514 of 3371

INFINITI QX56 2004 Factory Service Manual TROUBLE DIAGNOSIS
ATC-109
C
D
E
F
G
H
I
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MA
B
AT C
Revision: August 20072004 QX56
11 . CHECK VOLTAGE FOR FRONT AIR CONTROL (FAN ON SIGNAL)
1. Reconnect BCM connector and front air control connecto

Page 515 of 3371

INFINITI QX56 2004 Factory Service Manual 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

Page 516 of 3371

INFINITI QX56 2004 Factory Service Manual TROUBLE DIAGNOSIS
ATC-111
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
PERFORMANCE TEST DIAGNOSES
*1ATC-113, "PERFORMANCE
CHART"
*2AT C - 11 3 , "PERFORMANCE
CHART"
*3AT C - 11 4 , "

Page 517 of 3371

INFINITI QX56 2004 Factory Service Manual 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

Page 518 of 3371

INFINITI QX56 2004 Factory Service Manual TROUBLE DIAGNOSIS
ATC-113
C
D
E
F
G
H
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MA
B
AT C
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-disch

Page 519 of 3371

INFINITI QX56 2004 Factory Service Manual 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. Th

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

Page 520 of 3371

INFINITI QX56 2004 Factory Service Manual TROUBLE DIAGNOSIS
ATC-115
C
D
E
F
G
H
I
K
L
MA
B
AT C
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

TROUBLE DIAGNOSIS
ATC-115
C
D
E
F
G
H
I
K
L
MA
B
AT C
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

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