Nissan Murano: Ventilation, Heater & Air Conditioner / Heater & Air Conditioning System :: System Description. Refrigeration System

Component Parts Location

This unit combines the blower unit, heating unit, and cooling unit into an assembly.

Hot coolant from the engine is passed through a winding tube of the core. Fins attached to the core tubes serve to increase surface for heat transfer to air that is forced past them, by a fan, thereby heating the passenger compartment.

The refrigerant temperature is detected by the temperature sensing part located in low-pressure refrigerant path inside expansion valve. The lift amount of high-pressure side ball valve is changed to regulate the refrigerant flow.

• A thin laminate pipeless evaporator is used.

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

  

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

The sub-cool section further cools the liquid refrigerant, increasing the amount of heat that the liquid refrigerant can absorb and improving cooling performance.

• A liquid tank compatible with R-1234yf refrigerant is used.

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

Transfers heat out of the liquid refrigerant, sub cooling it below condensation temperature.

REFRIGERANT CYCLE

Refrigerant Flow

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

Freeze Protection

To prevent evaporator from freezing up, the evaporator air temperature is monitored and the voltage signal to the A/C auto amp. makes the A/C relay go OFF and stop the 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 liquid tank. 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 is detected by refrigerant pressure sensor to have the following conditions:

  • Approximately 3,120 kPa (31.8 kg/cm², 452 psi) or more (Engine speed is 1,500 rpm or more.)

  • Approximately 2,740 kPa (27.9 kg/cm², 397 psi) or more (Engine speed is less than 1,500 rpm.)

  • Approximately 120 kPa (1.2 kg/cm², 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/cm², 551 psi)].