Self Study Program 665 – Audi A8 (type 4N) New air conditioning features and introduction of refrigerant R744

VAG SSP 665. This self study programme describes the new features of the air conditioning system in the Audi A8 (type 4N), as well as the design and function of the air conditioning system filled with the new R744 refrigerant introduced in this model.

Carbon dioxide is used for the first time as an auxiliary refrigerant in the new Audi A8 (type 4N). It has different physical properties to the other refrigerants in use, e.g. it is non-flammable, colourless and odourless.

The refrigerant circuit continues to operate at much higher pressures. The components of the refrigerant circuit, such as the compressor and gas cooler, have adapted functions. The new Audi A8 (type 4N) also offers new in-car air quality features, such as a cabin fragrance system with selectable fragrances and an air improvement system.

Learning objectives of this self study programme:

Once you have completed this self study programme you will be able to answer questions on the following topics:

  • How is the air conditioning system configured for use of the new R744 refrigerant?
  • What are the points to note when servicing the cabin fragrance system function unit?
  • What are the new display and control features of the air conditioning system?
  • What new massage functions are available in the new Audi A8?


  • Introduction
    • Introduction of the new R744 refrigeran
    • Global Warming Potential
  • Design of the R744 air conditioning system
    • Schematic diagram and function description
    • AC compressor
    • Gas cooler
    • Internal heat exchanger
    • Pressure relief valve, low and high-pressure sides
    • Expansion valve
    • Evaporator
    • Accumulator
    • Refrigerant lines
    • Refrigerant pressure and temperature sensors G1052 / G1053
    • Cabin carbon dioxide level sensor G929
    • Components of the R744 refrigerant circuit
    • Topology
  • Aromatisation and air quality
    • Cabin fragrance system
    • Air improvement system
  • AC control panels in the front and rear
    • Front area
    • Rear area
  • Seats and surface heating
    • Massage function
    • Surface heating
    • Foot heater
    • Optional seat heating and ventilation
  • Workshop equipment
    • A/C service station
    • Service connections
  • Appendix
    • Self study programmes

The self study programme teaches a basic understanding of the design and mode of operation of new models, new automotive components or new technologies.
It is not a repair manual! Figures are given for explanatory purposes only and refer to the data valid at the time of preparation of the SSP.
This content is not updated.
For further information about maintenance and repair work, always refer to the current technical literature.

Language: English
Format: PDF
Pages: 36

Self Study Program 665 – Audi A8 (type 4N) New air conditioning features and introduction of refrigerant R744