Audi A4 Owners & Service Manuals

Audi A4: Compressor, Replacing without the Need for Flushing Refrigerant Circuit

Audi A4 (B9) 2016-2024 Service Manual / Heating, Ventilation & Air Conditioning / Refrigerant Circuit Components, Replacing / Compressor, Replacing without the Need for Flushing Refrigerant Circuit

  Note

  • Cleaning the refrigerant circuit means flushing with refrigerant R134a. Refer to → Chapter "Refrigerant Circuit, Cleaning (Flushing), with Refrigerant R134a".
  • If a faulty A/C compressor is replaced with an A/C compressor from another manufacturer check for the A/C compressor to be installed has the same refrigerant oil approved which is already in the refrigerant circuit (from the removed A/C compressor). If a different refrigerant oil is approved for the A/C compressor to be installed then the A/C compressor which was removed, the refrigerant circuit must be flushed. Refer to → Chapter "Approved Refrigerant Oils".

For example, in the event of external damage following an accident (or for an electrical fault).

- Discharge the refrigerant circuit.

- Remove the A/C compressor. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; A/C Compressor (vehicle-specific repair manual).

  Note

Use different refrigerant oils and quantities for the various compressors. Refer to → Chapter "Refrigerant Oil Capacities".

Electrically-Driven A/C compressor

  • When and electrically driven A/C compressor is replaced determine the amount of refrigerant oil found in the removed A/C compressor by flushing. Refer to → Chapter "Electrically Driven A/C Compressor, Rinsing (Remove Refrigerant Oil)". Pour the refrigerant oil out of the A/C compressor to be installed so that only the amount or refrigerant oil remains in the A/C compressor as the amount flushed out of the removed A/C compressor. Refer to → Chapter "Refrigerant Oil Capacities".

Example:

  • From the A/C compressor to be replaced 120 cm3 is flushed. Refer to → Chapter "Electrically Driven A/C Compressor, Rinsing (Remove Refrigerant Oil)".
  • In the A/C compressor to be installed there are 200 cm3 refrigerant oil. Refer to the data plate and → Chapter "Refrigerant Oil Capacities".

- Tip out from the new A/C compressor (next over the connection for the refrigerant pipe low pressure side) enough refrigerant that only the amount of refrigerant oil (plus 10 cm3) remains in it, as before the replaced A/C compressor was flushed out. An example is 110 cm3 refrigerant oil (this will insure that the refrigerant oil quantity in the refrigerant circuit after installing is correct).

  Note

  • Electrically driven A/C compressors cannot have the refrigerant oil poured out in the same manner as a mechanically driven A/C compressor. There is no drain plug, the A/C compression cannot be turned and because it is installed inside defending on the version only a specialized part or no refrigerant oil can be poured out. (Due to the different distribution of refrigerant oil in the A/C compressor). Usually a residual amount between 30 and 80 cm3 remains in the A/C compressor when pouring out. For this reason, the removed A/C compressor is to be flushed to remove the refrigerant oil and to determine the amount of refrigerant oil, depending on the complaint. Refer to → Chapter "Electrically Driven A/C Compressor, Rinsing (Remove Refrigerant Oil)".
  • If the recommended amount of refrigerant oil cannot be poured out of the A/C compressor to be installed if necessary the new A/C compressor to be installed may be flushed. In the new A/C compressor as much refrigerant oil the amount is to be filled as was flushed out of the old A/C compressor. Refer to → Chapter "Electrically Driven A/C Compressor, Rinsing (Remove Refrigerant Oil)".
  • At room temperature the refrigerant oil had approximately the same density as water (1 kg equals a liter).
  • Also electrical A/C compressors of the same version (same manufacturer, same part number) mostly do not have the same weight so that the amount of refrigerant oil contained cannot be determined by weighing (the tolerances are too large, to determine the amount of refrigerant oil contained via the weight).
  • Depending on the construction and the storage of the A/C compressor the refrigerant oil separated unevenly in the A/C compressor. One part can be located in the compression chamber and another in the area of the electronic motor, so that here the refrigerant oil must be alternately poured out via both connections for the refrigerant lines (high and low pressure side). While doing this arrange the A/C compressor so that the relevant connection is as far downward as possible.
  • Dispose of the refrigerant oil removed from the defective and the new A/C compressor and poured out refrigerant oil from the new A/C compressor which is no longer necessary. Pay attention to local regulations.

Mechanically Driven A/C Compressor

- Remove the drain plug from the A/C compressor (mechanically driven A/C compressor).

  Note

There are different versions of the oil drain plug and its seal (it can be either an O-ring or a gasket; always replace). Refer to → Chapter "Leaking or Damaged Components except A/C Compressor, Reservoir or Receiver/Dryer" and to the Parts Catalog.

- To accelerate drainage of refrigerant oil, rotate the A/C compressor by way of clutch plate of A/C clutch, for example.

- Drain the old refrigerant oil from the A/C compressor and dispose. Pay attention to local regulations.

- Remove the oil drain plug from replacement A/C compressor, pour out refrigerant oil in a clean container and only add a quantity of fresh refrigerant oil equal to the amount poured out of the malfunctioning A/C compressor.

  Caution

There is a risk of damaging the A/C compressor with dirty refrigerant oil.

  • Refrigerant oil that is poured out from the new A/C compressor can only be reused when it is located in a clean container and the necessary amount after pour out is refilled in the A/C compressor.
  • Do not reuse refrigerant oil when it is dirty or there is moisture, this is to be disposed of.

  Note

  • If, for example, 70 cm3 of refrigerant oil has been poured out of the defective A/C compressor and 220 cm 3 out of the replacement A/C compressor (a small quantity of refrigerant oil remains in the A/C compressor). In this case fill the A/C compressor that is to be installed with 70 cm 3 refrigerant oil. The refrigerant oil that was poured out of the new (replacement) A/C compressor can be reused, if there is no dirt of moisture in it.
  • Use different refrigerant oils and quantities for the various compressors. Refer to → Chapter "Refrigerant R134a Capacities, Refrigerant Oil and Approved Refrigerant Oils".
  • If a greater quantity of refrigerant oil (more than approximately 40 cm 3) has been poured out of the malfunctioning compressor, the remaining refrigerant oil can also be added to the evaporator or receiver/dryer. Refer to → Chapter "Refrigerant R134a Capacities, Refrigerant Oil and Approved Refrigerant Oils".

All

- Replace the restrictor (only if there is one in this refrigerant circuit).

- Assemble, evacuate and charge the refrigerant circuit.

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