Nissan Murano Z51. Instruction — part 823

HA-8

< SYMPTOM DIAGNOSIS >

REFRIGERATION SYSTEM SYMPTOMS

SYMPTOM DIAGNOSIS

REFRIGERATION SYSTEM SYMPTOMS

Trouble Diagnosis For Unusual Pressure

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Diagnose using a manifold gauge whenever the 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 pressure range. Refer to the
above table (Ambient air temperature-to-operating pressure table) since the standard pressure, however, dif-
fers from vehicle to vehicle.

Symptom Table

INFOID:0000000005514513

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Both high and low-pressure sides
are too high.

The pressure returns to nor-
mal and is reduced soon after
water is splashed on con-
denser.

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 the compressor is

stopped the 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 slightly

open compared with the
specification.

↓

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, the liquid tank is not
very 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

REFRIGERATION SYSTEM SYMPTOMS

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< SYMPTOM DIAGNOSIS >

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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.

Both high and low-pressure sides
are too low.

• There is a big temperature

difference between the liq-
uid tank outlet and inlet.
Outlet temperature is ex-
tremely 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
compared with areas near
the 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-29, "Refrigerant

Leakages"

.

There is a big temperature dif-
ference between the expan-
sion valve inlet and outlet
while the valve itself is frost-
ed.

Expansion valve slightly closes
compared with the specifica-
tion.

↓

1.

Improper expansion
valve adjustment.

2.

Malfunctioning expansion
valve.

3.

Outlet and inlet may be
clogged.

• Remove foreign materials 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 suffi-
cient or is too low.

Evaporator is frozen.

• Check intake sensor circuit.

Refer to

HAC-51, "Diagnosis

Procedure"

(without 7 inch

display) or

HAC-173, "Diag-

nosis Procedure"

(with 7 inch

display).

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

Refer to

HAC-69, "Diagnosis

Procedure"

(without 7 inch

display) or

HAC-191, "Diag-

nosis Procedure"

(with 7 inch

display).

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

AC356A

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 materials.
• Cooling is initially okay if wa-

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

• Remove expansion valve an-

dremove the particles with
dryand compressed air (not
shopair) if due to foreign par-
ticles.

• 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

COMPRESSOR SYSTEM SYMPTOMS

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COMPRESSOR SYSTEM SYMPTOMS

Symptom Table

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Follow the next table and perform trouble diagnosis if there is a compressor unit malfunction (internal noise,
insufficient cooling).

*1: First conduct inspection according to trouble diagnosis for each malfunction.
*2: Applicable to variable capacity compressor only.

Symptom

Inspection method

Check list

Result

Action

Noise from compressor unit
When A/C is ON.
(rattling or rolling sound)

Cooker system in-
ternal pressure

Check with manifold gauge

Both high- and low-
pressure sides are

high.

*2

Recharge with proper
amount of refrigerant.

High/low-pressures

hunt.

*2

Replace compressor
only.

Check compressor
oil condition.

Sample compressor oil and
judge.

Refer to the criteria
shown in compressor
lubricant.

Judgment result 1: Re-
place compressor only.

Judgement result 2:
Replace compressor
and liquid tank.

Insufficient cooling

*1

Compressor body

Check rotation of compressor.
If sized or stuck, sample com-
pressor oil and judge.

Cooler system inter-
nal pressure

Check with a manifold gauge.
Sample compressor oil and
judge if the difference between
high-pressure and low-pres-
sure is small or if they are al-
most the same.

Outlet air temperature rises

temporarily while driving.

*2

—

—

—

Replace compressor
only.

JSIIA0927GB