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Home >> Audi >> 2021 >> A4 Quattro Premium Plus, 2.0L Eng VIN B >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Air Conditioning (Refrigerant R134A Servicing) (2 Of 2) >> 87 Air Conditioning >> Refrigerant Circuit General Information >> Refrigerant Circuit Pressures And Temperatures >> Refrigerant Circuit With Expansion Valve

Refrigerant Circuit With Expansion Valve

NOTE:

Applies to vehicles with an Electrical A/C Compressor -V470- only with restrictions.

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Component Aggregate State of Refrigerant Pressure (positive pressure) Temperature
-1- Evaporator, from input to output Vapor approximately 1.2 bar (17 psi)(1)1 approximately -7 °C (-19.4 °F)(2)2
-2- Expansion valve Fluid, released as vapor approximately 14 bar (203 psi) approximately 55 °C (131 °F) HP- side, reduces to -7 °C (-19.4 °F) LP-side
-3- High pressure switch/high pressure sensor Fluid approximately 14 bar (203 psi) approximately 55 °C (131 °F)
-4- HP-side service connection and -5- Receiver/dryer Fluid approximately 14 bar (203 psi) approximately 55 °C (131 °F)
-6- Condenser From gas (at input) via vapor to fluid (at outlet) approximately 14 bar (203 psi) From approximately 65 °C (149 °F) at input to approximately 55 °C (131 °F) at outlet
-7- Pressure relief valve and -8- A/C compressor, HP-side Gas approximately 14 bar (203 psi) approximately 65 °C (149 °F)
-9- A/C compressor low pressure side Gas approximately 1.2 bar (17 psi)(1)1 approximately -1 °C (30 °F)(2)2
-10- Pre-volume (not present in all vehicles) and -11- LP-side service connection Gas approximately 1.2 bar (17 psi)(1)1 approximately -1 °C (30 °F)(2)2
(1) 1- Pressure in refrigerant circuits is maintained at approximately 2 bar (29 psi) absolute pressure (corresponds to approximately 1 bar (14.5 psi) positive pressure), 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. Refer to PRESSURES, CHECKING .
(2) 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 .
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.

Temperature and pressure in the refrigerant circuit in vehicles with two evaporators and two expansion valves correspond to those in vehicles with only one evaporator and one expansion valve (parallel switching).

Depending on the version of the refrigerant circuit, a component with an inner heat exchanger may be installed (for example, on the Audi A4 from MY 2008 and on the Audi A5 Coupe from MY 2008, a refrigerant line with an inner heat exchanger). Inside the inner heat exchanger, the flowing fluid warm refrigerant on the high pressure side is delivered into the low pressure side as flowing, vapor, cold refrigerant to increase the efficiency of the A/C system. Refer to REFRIGERANT LINE WITH INNER HEAT EXCHANGER .

Arrows point in direction of refrigerant flow.

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Fig 1: Identifying Refrigerant Circuit With Expansion Valve Overview
GWWA87-10139Courtesy of AUDI OF AMERICA, LLC
  1. Evaporator
  2. Expansion Valve
  3. High Pressure Switch/High Pressure Sensor
    • Different versions depending on vehicle
  4. Service Connection, HP Side
  5. Receiver/Dryer
    • Different versions depending on vehicle
  6. Condenser
  7. Pressure Relief Valve
  8. A/C Compressor, HP side
  9. A/C Compressor, LP side
  10. Pre-Volumes
    • Not present on all vehicles
  11. Service Connection, LP Side
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