Nissan Sentra. Manual — part 531

HA-18

< SYMPTOM DIAGNOSIS >

REFRIGERATION SYSTEM SYMPTOMS

REFRIGERATION SYSTEM SYMPTOMS

Trouble Diagnosis For Unusual Pressure

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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

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Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Both high and low pressure sides
are too high.

The pressure returns to nor-
mal soon after sprinkling wa-
ter on condenser.

Overfilled refrigerant.

Collect all refrigerant, evacuate
refrigerant cycle again, and
then refill it with the specified
amount of refrigerant.

Air flow to condenser is insuf-
ficient.

Insufficient condenser cooling
performance.
• Poor fan rotation of radiator

and condenser.

• Improper installation of air

guide.

• Clogged or dirty condenser

fins.

• Repair or replace malfunc-

tioning parts.

• Clean and repair condenser

fins.

When compressor is stopped,
a high-pressure reading
quickly drops by approximate-
ly 196 kPa (2 kg/cm

2

, 28 psi).

It then gradually decreases.

Air mixed in refrigerant cycle.

Collect all refrigerant, evacuate
refrigerant cycle again, and
then refill it with the specified
amount of refrigerant.

• Low-pressure pipe is cooler

than the outlet of evapora-
tor.

• Low-pressure pipe is frost-

ed.

Expansion valve opened too
much (excessive flow of refrig-
erant).

Replace expansion valve.

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

High-pressure pipe and upper
side of condenser become
hot, however, liquid tank does
not become so hot.

Clogged or crushed high-pres-
sure pipe located between
compressor and condenser.

Repair or replace the malfunc-
tioning parts.

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

• The readings of both sides

become equal soon after
compressor operation
stops.

• There is no temperature dif-

ference between high- and
low-pressure sides.

Malfunction in compressor sys-
tem (insufficient compressor
pressure operation).
• Damage or breakage of

valve.

• Malfunctioning gaskets.

Replace compressor.

AC359A

AC360A

AC356A

REFRIGERATION SYSTEM SYMPTOMS

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< SYMPTOM DIAGNOSIS >

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Both high and low pressure sides
are too low.

• The area around evapora-

tor outlet does not become
cold.

• The area around evapora-

tor inlet becomes frosted.

Clogged expansion valve.
• Breakage of temperature

sensor.

• Clogging by foreign material.

Eliminate foreign material from
expansion valve or replace it.

• There is a temperature dif-

ference between the areas
around outlet and inlet
pipes of liquid tank.

• Liquid tank becomes frost-

ed.

Malfunction in inner liquid tank
(clogged strainer).

Replace liquid tank.

Evaporator becomes frosted.

Clogged or crushed low-pres-
sure pipe.

Repair or replace malfunction-
ing parts.

Malfunction in intake air tem-
perature sensor.

Check intake sensor system.
Refer to

HAC-171, "Component

Inspection"

.

There is a small temperature
difference between the high
and low pressure pipes for re-
frigerant cycle.

• Shortage of refrigerant.
• Leakage of refrigerant.

• Check for leakage.
• Collect all refrigerant, evacu-

ate refrigerant cycle again,
and then refill it with the spec-
ified amount of refrigerant.

Low-pressure side sometimes be-
comes negative.

• Sometimes the area

around evaporator outlet
does not become cold.

• Sometimes the area

around evaporator inlet is
frosted.

• Icing caused by the mixing of

water in cooler cycle.

• Deteriorated dryer in liquid

tank.

• Collect all refrigerant.
• Evacuate refrigerant cycle

completely, and then refill it
with the specified amount of
refrigerant. At this time, al-
ways replace liquid tank.

Hunting in high-pressure side.

There is no temperature dif-
ference between high- and
low-pressure sides.

Malfunctioning variable valve
in compressor.

• Replace compressor.
• Check ECV system.

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

AC353A

AC354A

HA-20

< SYMPTOM DIAGNOSIS >

NOISE

NOISE

Symptom Table

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Symptom

Noise source

Probable cause

Corrective action

Unusual noise from compressor
when A/C is ON.

Inside of compressor

Wear, breakage or clogging of foreign
material in inner parts.

Check compressor oil. Re-
fer to

HA-25, "Inspection"

.

Magnet clutch

Contact of clutch disc with pulley.

Check clearance between
clutch disc and pulley.

Compressor body

Loosened compressor mounting bolts.

Check bolts for tightness.
Refer to

HA-30, "Exploded

View"

.

Unusual noise from cooler piping.

Cooler piping (pipe and
flexible hose)

Improper installation of clip and brack-
et.

Check the installation condi-
tion of the cooler piping. Re-
fer to

HA-35, "Exploded

View"

.

Unusual noise from expansion
valve when A/C is ON.

Expansion valve

Shortage of refrigerant.

• Check for leakage.
• Collect all refrigerant,

evacuate refrigerant cycle
again, and then refill it
with the specified amount
of refrigerant.

Wear, breakage or clogging of foreign
material in inner parts.

Eliminate foreign material
from expansion valve or re-
place it.

Unusual noise from belt.

—

Loosened belt

Check belt tension. Refer to

EM-16, "Inspection"

.

Internal compressor parts get locked

Replace compressor. Refer
to

HA-31, "COMPRESSOR

: Removal and Installation"

.

REFRIGERANT

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PERIODIC MAINTENANCE

REFRIGERANT

Description

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CONNECTION OF SERVICE TOOLS AND EQUIPMENT

Leak Test

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CHECK REFRIGERANT LEAKAGE USING FLUORESCENT LEAK DETECTION DYE

1. Install a fender cover (1).
2. Wear UV safety goggles (2) provided with refrigerant dye leak detection kit (J-43926).
3. Connect power cable (4) of UV lamp (6) to positive and negative terminals of the battery (3).

1.

Shut-off valve

2.

A/C service valve

3.

Recovery/recycling/recharging
equipment

4.

Refrigerant container (HFC-134a)

5.

Weight scale (J-39650)

6.

Vacuum pump (J-39649)

7.

Manifold gauge set (J-39183)

A.

Preferred (best) method

B.

Alternative method

C.

For charging

JSIIA0239ZZ

RJIA3815J