Audi A4 Owners & Service Manuals

Audi A4: Vehicles with a High Voltage System (Hybrid Vehicles)

Extremely Dangerous Due to High-Voltage

The high-voltage system is under high-voltage. Death or serious bodily injury by electric shock.

- Individuals with electronic/medical life- and health sustaining machines in or on their person cannot perform any work on high-voltage systems. Life- and health sustaining machines are for example pain killer pumps, implanted defibrillators, pacemakers, insulin pumps, and hearing aids.

- Have the high-voltage system de-energized by a qualified person.

There is a Risk of Injury from the Engine Starting Unexpectedly

On electric - hybrid vehicles an active ready mode is difficult to identify. Parts of the body can be clamped or pulled.

- Turn off the ignition.

- Place the ignition key outside of the vehicle interior.

Risk of Damaging the High-Voltage Cables

Misuse can damage the insulation of high-voltage cables or high-voltage connectors.

- Never support objects on the high-voltage cables and the high-voltage connectors.

- Never support tools on the high-voltage cables and the high-voltage connectors.

- Never sharply bend or kink the high-voltage cables.

- When connecting pay attention to the coding of the high-voltage connectors.

  • For all procedures on vehicles with high-voltage system pay attention to the additional warning message for these vehicles. Refer to → Chapter "Warnings when Working on Vehicles with High Voltage System".
  • If procedures are necessary near components of the high-voltage system "perform a visual inspection of the damage of the high-voltage components and lines". Refer to → Chapter "Performing a Visual Inspection of Damage to High Voltage Components and Cables".
  • If work on the components of the high-voltage system is necessity, de-energize the high-voltage system. Refer to → Rep. Gr.93; High-Voltage System, De-Energizing or → Electrical Equipment; Rep. Gr.93; High-Voltage System, De-Energizing.

Vehicles with Start/Stop System

There is a Risk of Injury from the Engine Starting Unexpectedly

The engine can start unexpectedly on vehicles with an activated Start/Stop System. A message appears in the instrument cluster indicating whether the Start/Stop System is activated.

- Deactivate the Start/Stop System: Turn off the ignition.

Refrigerant Circuit Components


Non-approved tools or materials such as leak sealing additives can cause damage or malfunctions in the system.

Only use tools and materials approved by the manufacturer.

The warranty is voided if non-approved tools or materials are used.

  • Any refrigerant circuit components submitted for quality observation must be sealed (use the caps that come with the replacement part).
  • Replace damaged or leaking components of the refrigerant circuit. Refer to → Chapter "Refrigerant Circuit Components, Replacing".


To date, the following replacement parts (A/C compressor, reservoir, evaporator and condenser) are filled with nitrogen gas. This charge is being gradually discontinued. Little or no pressure equalization is therefore noticeable on unscrewing sealing plugs from replacement parts.


     Refrigerant Circuit Components Allocation, High and Low Pressure Sides

     General Information

    High pressure side are the condenser, receiver/dryer and restrictor or expansion valve to separate the high and low pressure liquid ends. High pressure results from the restrictor or expansion valve


    The condenser conducts heat from compressed refrigerant gas to the ambient air. This condenses the refrigerant gas to fluid.   Note Depending on the version of the refrigerant circuit, the r


     Backrest Adjuster, Removing and Installing

    Backrest Adjustment Hand Wheel, Removing and Installing Special tools and workshop equipment required Assembly Tool -3399- Removing - Move the front seat all the way forward into its highest position. - Turn the backrest adjustment wheel -1- until one catch is visible from behind -ar

     General Safety Precautions

    As per VBG 20, German industrial liability insurance association. Pay attention to the workshop-specific instructions. It should be kept in the workshop. Product Characteristics Refrigerants used in motor vehicle air conditioning systems belong to the new generation of refrigerants based on

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