Nissan Maxima Service and Repair Manual: System description

REFRIGERATION SYSTEM

Refrigerant Cycle

Refrigerant flow

1. Compressor
2. Pressure relief valve
3. Liquid tank
4. Refrigerant pressure sensor
5. Condenser
6. Expansion valve
7. Evaporator
8. Blower motor
1. High-pressure gas
2.  High-pressure liquid
3.  Low-pressure liquid
4.  Low-pressure gas
5.  Suction port
6.  Discharge port
7. Outside air

The refrigerant from the compressor flows through the condenser with liquid tank, the evaporator and returns to the compressor. The refrigerant evaporation in the evaporator is controlled by an expansion valve.

Component Part Location

1. Heater and cooling unit assembly
2. High-pressure pipe
3. High-pressure A/C service valve
4. High-pressure flexible hose
5. Air deflector (RH)
6. Junction pipe
7. Condenser
8. Liquid tank
9. Refrigerant pressure sensor
10. Condenser, liquid tank and refrigerant pressure sensor
11. Air deflector (LH)
12. Compressor
13. Low-pressure flexible hose
14. Low-pressure A/C service valve
15. Low-pressure pipe
1.  High-pressure pipe to heater and cooling unit assembly
2. . High-pressure flexible hose to compressor
3.  Low-pressure flexible hose to compressor

Refrigerant System Protection

Refrigerant pressure sensor

The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sensor, located on the condenser. If the system pressure rises above or falls below the specifications, the refrigerant pressure sensor detects the pressure inside the refrigerant line and sends the voltage signal to the ECM.

The ECM then ceases to supply power to the A/C relay which disengages and stops the compressor when pressure on the high pressure side (as detected by refrigerant pressure sensor) is over approximately 2,746 kPa (28 kg/cm2, 398 psi), or below approximately 120 kPa (1.22 kg/cm2, 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 3,727 kPa (38 kg/ cm2, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere.