Audi A4 Owners & Service Manuals

Audi A4: General Information

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.

  Note

The following steps using the A/C service station (checking pressures) on the refrigerant circuit can only be performed while the drive ready mode is active. If necessary, restart the high voltage system.

- 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 the Battery and → Electrical Equipment; Rep. Gr.93; General Notes for Working on the High Voltage System.

- Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

  Note

  • Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active.
  • The ready mode is displayed in the Instrument Cluster Control Module -J285- above the "powermeter". Refer to Owner's Manual.
  • Activate and deactivate the ready mode. Refer to Owner's Manual (consult the display in the Instrument Cluster Control Module -J285-).

- Turn off the ignition.

  Note

If a malfunction occurs at only one evaporator in vehicles with two evaporators (one evaporator in the A/C unit and the other in the battery cooling module or in the high voltage battery heat exchanger), also check pressures in the refrigerant circuit, are these OK? Check the line connection between the evaporator in question and the exit of line connection at distribution point of refrigerant lines (for constriction or blockage, for example in the refrigerant line restrictor to the high voltage battery heat exchanger). If no malfunction can be detected, discharge the refrigerant circuit and charge it with the specified refrigerant quantity. Then check the pressures and A/C system cooling output again; if the malfunction occurs again, check/replace the following components: if the complaint is only occurs at the evaporator in the A/C unit, the shut-off valve is prematurely switched by the evaporator (for example Hybrid Battery Refrigerant Shut-Off Valve 1 -N516- or the Heater and A/C Unit Refrigerant Cut-Off Valve -N541-). This component is open when it is not activated and allows the refrigerant to flow through. Replace the expansion valve on the evaporator in the A/C unit, if no fault can be found on the Hybrid Battery Refrigerant Shut-Off Valve 1 -N516-/Heater and A/C Unit Refrigerant Cut-Off Valve -N541-. If a malfunction occurs only on the evaporator for the cooling the high voltage components (for example in the battery cooling module), check the activation of the Hybrid Battery Refrigerant Shut-Off Valve 2 -N517- on the evaporator expansion valve in the battery cooling module (it is closed when it is not activated and does not allow the refrigerant to flow through). If the malfunction only occurs on the high voltage battery heat exchanger, check the High Voltage Battery Heater Core Refrigerant Cut-Off Valve -N542- (it is open when it is not activated and allows the refrigerant to flow through) and the restrictor installed in the refrigerant line. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; System Overview - Refrigerant Circuit (vehicle-specific repair manual).

- With the ignition switched off, check the pressure in the refrigerant circuit (using the service station). Refer to → Chapter "Refrigerant Circuit, Checking Pressure with Service Station".

The pressures with the ignition turned off meet the specifications.

- 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 the Battery and → Electrical Equipment; Rep. Gr.93; General Notes for Working on the High Voltage System.

  Note

  • Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active.
  • The engine must not be running when checking the pressures in the refrigerant circuit on vehicles with a high voltage system.
  • The ready mode is displayed in the Instrument Cluster Control Module -J285- above the "power meter". Refer to Owner's Manual.
  • Activate the ready mode (and observe the display in the Instrument Cluster Control Module -J285-). Refer to the Owner's Manual.

- Activate the drive ready mode. Refer to the Owner's Manual.

- Switch on the A/C system.

- Observe the pressure gauge of the service station.

  Note

  • The activation of the electrically driven A/C compressor occurs from the vehicle electrical system. The engine RPM does not have any effect on the A/C cooling output.
  • The A/C compressor is not actuated at the maximum specified speed (of approximately 8500/min) on a stationary or slow moving vehicle (up to a speed of approximately 45km/h) (the A/C compressor speed is limited to approximately 5000/min).
  • The activation of the electrically driven A/C compressor can be monitored by the "Guided Fault Finding" using the Vehicle Diagnostic Tester Function for A/C System and the Battery Regulation.
  • Pressures must be measured at service connections; component locations of these connections are vehicle-specific. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; System Overview - Refrigerant Circuit (vehicle-specific repair manual).

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