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Refrigerant Circuit With Expansion Valve

A- Low pressure side of refrigerant circuit.

B- High pressure side of refrigerant circuit

Fig 1: Identifying A/C Refrigerant System Pressure Diagram
GWWN00-10142Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
Component Aggregate state of refrigerant Pressure (bar positive pressure) Temperature in degrees Celsius
-1- Evaporator, from input to output Vapor approximately 1.2 bar (1) approximately -7°C (20 °F) (2)
    (approximately 1.8 bar) (3) approximately -1 °C (30 °F) (3)
-2- A/C compressor A-side Gas approximately 1.2 bar (1) approximately -1 °C (30 °F)
    (approximately 1.8 bar) (3) approximately -1 °C (30 °F) (3)
-3- A/C compressor B-side Gas approximately 14 bar approximately + 149 °F (65 °C)
-4- Condenser Gas, vapor, fluid approximately 14 bar approximately + 55 °C (131 °F) at outlet
-5- Receiver Fluid approximately 14 bar approximately + 55 °C (131 °F)
-6- Extraction and filling valve, B-side Fluid approximately 14 bar approximately + 55 °C (131 °F)
-7- Expansion valve Fluid, released as vapor approximately 14 bar approximately + 55 °C (131 °F), reduced to -7°C (20 °F)
-8- Extraction and filling valve, A-side Gas approximately 1.2 bar (1) approximately -7°C (20 °F) (2)
    (approximately 1.8 bar) (3) approximately -1 °C (30 °F) (3)
(1) Pressure in refrigerant circuits is maintained at approximately 2 bar, regulated by A/C compressor, even though heat transfer changes and engine speeds vary. However, this applies only within the performance range of the A/C compressor; if the performance limits of the A/C compressor are exceeded, the pressure increases PRESSURES, CHECKING .
(2) Within the control range of the A/C compressor, temperature in the refrigerant circuits is maintained, regulated by A/C compressor, even though heat transfer changes and engine speeds vary. However, this applies only within the performance range of the A/C compressor; if the performance limits of the A/C compressor are exceeded, the temperature increases PRESSURES, CHECKING .
(3) Measured values for A/C systems with two evaporators
NOTE:

A/C compressors which do not regulate their performance are switched off by the respective control module via the A/C compressor regulator valve -N280- at an evaporator temperature below 0 °C (32 °F).

In vehicles with A/C compressor regulator valve -N280-, the pressure is modified on the low pressure side by the valve.

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