Infiniti EX35. Manual — part 887

REFRIGERATION SYSTEM SYMPTOMS

HA-7

< SYMPTOM DIAGNOSIS >

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SYMPTOM DIAGNOSIS

REFRIGERATION SYSTEM SYMPTOMS

Trouble Diagnosis For Unusual Pressure

INFOID:0000000003545451

Diagnose using a manifold gauge whenever system’s high and/or low side pressure(s) is/are unusual. The
marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Refer to
above table (Ambient air temperature-to-operating pressure table) since the standard (usual) pressure, how-
ever, differs from vehicle to vehicle.

Symptom Table

INFOID:0000000003545452

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Both high- and low-pressure sides
are too high.

The pressure returns to nor-
mal is reduced soon after wa-
ter is splashed on condenser.

Excessive refrigerant charge in
refrigeration cycle.

Reduce refrigerant until speci-
fied pressure is obtained.

Air suction by cooling fan is in-
sufficient.

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
reading quickly drops by
approximately 196 kPa (2

kg/cm

2

, 28 psi). It then de-

creases gradually thereaf-
ter.

Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure decreas-
es too slowly).

↓

Air in refrigeration cycle.

Evacuate repeatedly and re-
charge system.

Engine tends to overheat.

Engine cooling systems mal-
function.

Check and repair each engine
cooling system.

• An area of the low-pressure

pipe is colder than areas
near the evaporator outlet.

• Low-pressure pipe is some-

times covered with frost.

• Excessive liquid refrigerant

on low-pressure side.

• Excessive refrigerant dis-

charge flow.

• Expansion valve is open a lit-

tle compared with the speci-
fication.

↓

Improper expansion valve ad-
justment.

Replace expansion valve.

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 lo-
cated between compressor
and condenser are clogged or
crushed.

• Check and repair or replace

malfunctioning parts.

• Check lubricant for contami-

nation.

AC359A

AC360A

HA-8

< SYMPTOM DIAGNOSIS >

REFRIGERATION SYSTEM SYMPTOMS

High-pressure side is too low and
low-pressure side is too high.

High- and low-pressure sides
become equal soon after
compressor operation stops.

Compressor pressure opera-
tion is improper.

↓

Damaged inside compressor
packings.

Replace compressor.

No temperature difference be-
tween high- and low-pressure
sides.

Compressor pressure opera-
tion is improper.

↓

Damaged inside compressor
packings.

Replace compressor.

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

AC356A

REFRIGERATION SYSTEM SYMPTOMS

HA-9

< SYMPTOM DIAGNOSIS >

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Both high- and low-pressure sides
are too low.

• There is a big temperature

difference between liquid
tank 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.

• Expansion valve inlet tem-

perature is extremely low
as compared with areas
near liquid tank.

• Expansion valve inlet is

frosted.

• Temperature difference oc-

curs somewhere in high-
pressure side.

High-pressure pipe located be-
tween liquid tank and expan-
sion valve is clogged.

• Check and repair malfunc-

tioning parts.

• Check lubricant for contami-

nation.

Expansion valve and liquid
tank are warm or slightly cool
when touched.

Low refrigerant charge.

↓

Leaking fittings or components.

Check refrigerant for leakages.
Refer to

HA-34, "Refrigerant

Leakages"

.

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.

• Replace expansion valve.
• 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 not enough
or is too low.

Evaporator is frozen.

• Check intake sensor circuit.

Refer to

HAC-100, "Diagno-

sis Procedure"

.

• Replace compressor.
• Repair evaporator fins.
• Replace evaporator.
• Check blower motor circuit.

Refer to

HAC-81, "WITHOUT

LEFT AND RIGHT VENTILA-
TION TEMPERATURE SEP-
ARATELY CONTROL
SYSTEM : Diagnosis Proce-
dure"

(Without left and right

ventilation temperature sepa-
rately control system) or

HAC-84, "WITH LEFT AND
RIGHT VENTILATION TEM-
PERATURE SEPARATELY
CONTROL SYSTEM : Diag-
nosis Procedure"

(With left

and right ventilation tempera-
ture separately control sys-
tem).

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

AC353A

HA-10

< SYMPTOM DIAGNOSIS >

REFRIGERATION SYSTEM SYMPTOMS

Low-pressure side sometimes be-
comes negative.

• Air conditioning system

does not function and does
not cyclically cool the com-
partment air.

• The system constantly

functions for a period of
time after compressor is
stopped and restarted.

Refrigerant does not discharge
cyclically.

↓

Moisture is frozen at expansion
valve outlet and inlet.

↓

Water is mixed with refrigerant.

• Drain water from refrigerant

or replace refrigerant.

• Replace liquid tank.

Low-pressure side becomes nega-
tive.

Liquid tank or front/rear side
of expansion valve’s pipe is
frosted or wet with dew.

High-pressure side is closed
and refrigerant does not flow.

↓

Expansion valve or liquid tank
is frosted.

Leave the system at rest until
no frost is present. Start it again
to check whether or not the mal-
function is caused by water or
foreign particles.
• Cooling is initially okay if wa-

ter is the cause. Then the wa-
ter freezes causing a
blockage. Drain water from
refrigerant or replace refriger-
ant.

• Remove expansion valve and

remove the particles with dry
and compressed air (not shop
air) if due to foreign particles.

• Replace expansion valve if

either of the above methods
cannot correct the malfunc-
tion.

• Replace liquid tank.
• Check lubricant for contami-

nation.

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

AC354A

AC362A