Infiniti QX56 (JA60). Manual - part 578

 

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Infiniti QX56 (JA60). Manual - part 578

 

 

REFRIGERATION SYSTEM

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FUNCTION DIAGNOSIS

REFRIGERATION SYSTEM

Refrigerant Cycle

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REFRIGERANT FLOW

The refrigerant flows in the standard pattern, that is, through the compressor, the condenser with liquid tank,

through the front and rear evaporators, and back to the compressor. The refrigerant evaporation through the

evaporator coils are controlled by front and rear externally equalized expansion valves, located inside the front

and rear evaporator cases.

Refrigerant System Protection

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REFRIGERANT PRESSURE SENSOR

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

sor, located on the condenser. If the system pressure rises above or falls below the specifications, the refriger-

ant pressure sensor detects the pressure inside the refrigerant line and sends a voltage signal to the ECM.

The ECM de-energizes the A/C relay to disengage the magnetic compressor clutch when pressure on the high

WJIA1342E

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< FUNCTION DIAGNOSIS >

REFRIGERATION SYSTEM

pressure side detected by refrigerant pressure sensor is over about 2,746 kPa (28 kg/cm

2

, 398 psi), or below

about 120 kPa (1.22 kg/cm

2

, 17.4 psi).

PRESSURE RELIEF VALVE

The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compressor.

When the pressure of refrigerant in the system increases to an abnormal level [more than 2,990 kPa (30.5 kg/
cm

2

, 433.6 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into

the atmosphere.

OIL

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OIL

Maintenance of Oil in Compressor

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The oil in the compressor circulates through the system with the refrigerant. Add oil to compressor when

replacing any component or after a large refrigerant leakage has occurred. It is important to maintain the spec-

ified amount.

If oil quantity is not maintained properly, the following malfunctions may result:

• Lack of oil: May lead to a seized compressor

• Excessive oil: Inadequate cooling (thermal exchange interference)

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REFRIGERATION SYSTEM

ON-VEHICLE MAINTENANCE

REFRIGERATION SYSTEM

HFC-134a (R-134a) Service Procedure

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SETTING OF SERVICE TOOLS AND EQUIPMENT

Discharging Refrigerant

WARNING:

Avoid breathing A/C refrigerant and oil vapor or mist. Exposure may irritate eyes, nose and throat.

Remove HFC-134a (R-134a) refrigerant from the A/C system using certified service equipment meeting

requirements of SAE J2210 HFC-134a (R-134a) recycling equipment or SAE J2201 HFC-134a (R-134a)

recovery equipment. If an accidental system discharge occurs, ventilate the work area before resum-

ing service. Additional health and safety information may be obtained from the refrigerant and oil man-

ufacturers.

Evacuating System and Charging Refrigerant

1.

Shut-off valve

2.

A/C service valve

3.

Recovery/recycling equipment

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Content   ..  576  577  578  579   ..