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Nissan Cube. Manual - part 529

REFRIGERATION SYSTEM

HA-5

< SYSTEM DESCRIPTION >

SYSTEM DESCRIPTION

REFRIGERATION SYSTEM

System Diagram

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System Description

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REFRIGERANT CYCLE

Refrigerant Flow

The refrigerant flows from the compressor, through the condenser with liquid tank, through the evaporator, and
back to the compressor. The refrigerant evaporation in the evaporator is controlled by an externally equalized
expansion valve, located inside the evaporator case.

Freeze Protection

Automatic air conditioner

• When intake sensor detects that evaporator surface temperature is 2

C (36

F) or less, A/C auto amp.

requests BCM to turn the compressor OFF.

• BCM requests ECM to turn the compressor to OFF by the signal from A/C auto amp., and ECM makes A/C

relay to OFF, and stops the compressor.

Manual air conditioner

• When thermo control amp. detects that evaporator surface temperature becomes 2

C (36

F) or less, BCM

requests ECM to turn the compressor OFF, and stops the compressor.

REFRIGERANT SYSTEM PROTECTION

Refrigerant Pressure Sensor

• The refrigerant system is protected against excessively high- or low-pressures by the refrigerant pressure

sensor, installed at the condenser exit. The refrigerant pressure sensor detects the pressure inside the
refrigerant line and sends the voltage signal to the ECM if the system pressure rises above, or falls below
the specifications.

• ECM turns the A/C relay to OFF and stops the compressor when the high-pressure side detected by refriger-

ant pressure sensor is following conditions;

JPIIA1671GB

HA-6

< SYSTEM DESCRIPTION >

REFRIGERATION SYSTEM

- Approximately 3,120 kPa (31.8 kg/cm

, 452 psi) or more (Engine speed is less than 1,500 rpm.)

- Approximately 2,740 kPa (27.9 kg/cm

, 397 psi) or more (Engine speed is 1,500 rpm or more.)

- Approximately 120 kPa (1.2 kg/cm

, 17 psi) or less

Pressure Relief Valve

The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compressor.
The release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere
when the pressure of refrigerant in the system increases to an unusual level [more than 3,800 kPa (38.8 kg/
cm

, 551 psi)].

Component Parts Location

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Component Description

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JPIIA1718ZZ

Expansion valve

Condenser

Compressor

Refrigerant pressure sensor

Liquid tank

Evaporator

Built-in heater & cooling unit assem-
bly

Component

Description

Evaporator

The mist form liquid refrigerant transforms to gas by evaporation by the air conveyed from blower
motor. The air is cooled by the heat by evaporation.

Condenser

Cools refrigerant discharged from compressor, and transforms it to liquid refrigerant.

Compressor

Intakes, compresses, and discharges refrigerant, to circulate refrigerant inside the refrigerant cycle.

Refrigerant pressure sensor

Refer to

EC-425, "Description"

REFRIGERATION SYSTEM

HA-7

< SYSTEM DESCRIPTION >

Liquid tank

Eliminates foreign matter in refrigerant, and stores temporarily liquid refrigerant.

Expansion valve

Transforms high-pressure liquid refrigerant to mist form low-pressure liquid refrigerant by drawing
function.

Component

Description

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 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

, 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

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