Audi A4 Owners & Service Manuals

Audi A4: Refrigerant Circuit, General Precautions

General Information

  • Ensure absolute cleanliness when working.
  • Wear safety goggles and gloves when working with refrigerant and nitrogen.
  • Workshop extraction systems are to be switched on.
  • Use the service station to discharge the refrigerant circuit, only then open screw connections and replace the malfunctioning components.
  • Use a cap to seal off any opened assemblies and hoses to prevent moisture and dirt from getting in.
  • Make exclusive use of tools and materials intended for refrigerant R134a.
  • Seal opened refrigerant oil containers to guard against moisture.

  Note

  • After engine all service work, screw sealing caps (with seals) onto all connections with valve and service connections.
  • Before starting up A/C system. Observe vehicle specific filling capacities. Refer to → Chapter "Refrigerant R134a Capacities, Refrigerant Oil and Approved Refrigerant Oils".
  • Do not fill refrigerant, extract the refrigerant present and refill the system.

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.

All Vehicles

  • General Information. Refer to → Chapter "General Information".
  • Refrigerant Circuit, Cleaning. Refer to → Chapter "Refrigerant Circuit, Cleaning".
  • Additional notes for vehicles with A/C compressor without A/C clutch (with A/C Compressor Regulator Valve -N280-). Refer to → Chapter "Additional Information for Vehicles with A/C Compressor without A/C Clutch, (only with A/C Compressor Regulator Valve -N280-)".
  • O-ring seals. Refer to → Chapter "O-Ring Seals".

Refrigerant Circuit, Cleaning

Cleaning the refrigerant circuit with refrigerant R134a (flushing with refrigerant R134a). Refer to → Chapter "Refrigerant Circuit, Cleaning (Flushing), with Refrigerant R134a". (Or blow out with compressed air and nitrogen). Refer to → Chapter "Refrigerant Circuit, Flushing with Compressed Air and Nitrogen". In the event of:

- Moisture or dirt has gotten into the refrigerant circuit, for example, after a crash.

- Refrigerant oil is dark and viscous.

- There is too much refrigerant oil in the refrigerant circuit after replacing the compressor.

- The A/C compressor had to be replaced due to "internal" damage (for example, noises or no output).

  Note

When flushing components with compressed air and nitrogen, extract the gas mixture escaping from the components thoroughly via an existing exhaust-extraction ventilation system (workshop extraction system).

Additional Information for Vehicles with A/C Compressor without A/C Clutch, (only with A/C Compressor Regulator Valve -N280-)

  • The engine can be started only after the refrigerant circuit has been completely assembled (the A/C compressor runs continuously).
  • If the engine has to be operated with the refrigerant circuit empty, only do so for as long as absolutely essential and avoid high engine speeds.

Additional Information for Vehicles with High Voltage System

Vehicles with a high-voltage system (hybrid vehicles)

Extremely Dangerous Due to High-Voltage

The high-voltage system is under high-voltage. Electrocution can cause death or very serious personal injury from damages high-voltage components and high-voltage cables.

- Perform a visual inspection of the high-voltage components and the high-voltage cables.

- Never use tools that are for cutting, deformed, or sharp edged.

- Never use welding, soldering, thermal adhesive or hot air.

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".
  • Procedures necessary near the components of the high-voltage system. Refer to → Chapter "Performing a Visual Inspection of Damage to High Voltage Components and Cables" and → Rep. Gr.00; Safety Precautions or → Electrical Equipment; Rep. Gr.93; High Voltage System General Warnings.
  • Further information about the high-voltage system. Refer to → Rep. Gr.00; Safety Precautions or → Electrical Equipment; Rep. Gr.93; General Warnings for Working on High-Voltage System.
  • If procedures on components of the high-voltage system are required, de-energize the high-voltage system. Refer to → Rep. Gr.00; Safety Precautions or → Electrical Equipment; Rep. Gr.93; High Voltage System General Warnings.
  • The engine may only be started if the refrigerant circuit is completely assembled.
  • Hybrid drive on vehicles with battery cooling is only possible with a full A/C system in which there are no stored errors. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system and the battery regulation.
  • After the installation of the electrically-driven A/C compressor and the subsequent filling of the refrigerant circuit, start the A/C compressor for the first time using the "compressor intake" function for the basic setting. If the refrigerant oil was improperly stored before installation in the A/C compressor compression chamber, the A/C compressor may become damaged. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system and the battery regulation.
  • Only activate the electrically-driven A/C compressor when the refrigerant circuit is filled. The A/C compressor may become damaged if the A/C compressor is run when the refrigerant circuit is empty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function for the A/C system and the battery regulation.
  • So that the refrigerant circuit can be emptied, evacuated and filled depending on the design of the refrigerant circuit different electric controlled valves must be opened (for example on the Audi Q7 e-tron). Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
  • For checking the A/C function specific electric controlled valves must be opened or closed (for example on the Audi Q7 e-tron). Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.
  • The service connection on the high pressure side depends on the vehicle, not all operating conditions of the A/C system are on high pressure (for example on the Audi Q7 e-tron). For this reason to check the A/C function in these vehicles the sensor installed in the refrigerant circuit must be used. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

- Charge the vehicle battery, for example, using the Battery Charger -VAS5904- in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to → Electrical Equipment General Information; Rep. Gr.27; Battery, Charging and → High Voltage Vehicle General Information; Rep. Gr.93; High-Voltage System General Warnings.

- For testing and measurement procedures that require the ready mode to be active or the ignition to be switched on, the selector lever must be in the "P" position and the parking brake must be activated. The required tools must be placed so that they do not come into contact with any rotating components in the engine and they must also not go into the vicinity of the rotating components when the engine is running.

O-Ring Seals

  • Make exclusive use of seals which are resistant to refrigerant R134a and the related refrigerant oils. Color coding of O-rings is no longer employed. Colored and black O-rings are used.
  • Be sure to use seals with the correct inner diameter. Refer to the Parts Catalog and → Heating, Ventilation and Air Conditioning; Rep. Gr.87; System Overview - Refrigerant Circuit (vehicle-specific repair manual).
  • The O-rings may be used only one time.
  • Coat the seals lightly with refrigerant oil (PAG oil) before installing.

After Charging A/C System

Mechanically Driven A/C Compressor

After installing the A/C Compressor to the engine (before positioning the belt or installing the driveshaft) Refer to → Chapter "A/C System, Operating after Charging" and → Heating, Ventilation and Air Conditioning; Rep. Gr.87; A/C Compressor.

- Turn the A/C compressor by hand via the clutch plate or belt pulley on the A/C clutch approximately 10 turns.

After charging. Refer to → Chapter "A/C System, Operating after Charging".

- Start the engine with the A/C turned off (A/C Clutch -N25- and A/C Compressor Regulator Valve -N280- are not actuated).

- Following engine idling speed stabilization, switch on A/C compressor and run it for at least 10 minutes at idling speed with maximum cooling output.

Electrically Driven A/C Compressor

- First start the electrically driven A/C compressor after filling the refrigerant circuit via the "Compressor Cut-In" function from the basic setting. Refer to → Chapter "A/C System, Operating after Charging" and Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Regulation.

    READ NEXT:

     Refrigerant Circuit General Information

     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 su

     Refrigerant Circuit Components Allocation, High and Low Pressure Sides

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