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| The replacement compressor contains a certain amount of refrigeration oil (currently 130 + / - 10 cm3 depending on the air conditioner compressor, refer to rating plate). With the exception of vehicles with an 8-cyl. TDI engine, this quantity of refrigeration oil corresponds at present to the quantity of oil specified for this refrigerant circuit on vehicles with one or two evaporators (see below for vehicles with an 8-cyl. TDI engine). At present, vehicles with two evaporators are filled with the same amount of oil as vehicles with one evaporator. On account of the longer refrigerant lines and the second evaporator, no greater quantity of refrigerant oil is currently required in the refrigerant circuit on this vehicle. With this vehicle, the design of the refrigerant circuit means that only a small proportion of the refrigerant oil passes into the refrigerant lines to the second evaporator and into the second evaporator during air conditioner operation. If the air conditioner compressor is replaced after cleaning the refrigerant circuit, it is therefore not necessary on vehicles with two evaporators (on account of the second evaporator) to pour additional refrigeration oil into the refrigerant circuit. If the air conditioner compressor is replaced without having to clean the refrigerant circuit, the quantity of refrigerant oil in the new air conditioner compressor to be fitted should be adjusted in line with the quantity of oil poured out of the old compressor → Chapter. |
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| On vehicles with an 8-cyl. TDI engine, the quantity of refrigeration oil in the refrigerant circuit was increased as of vehicle identification number 4H_ BN 018846 from 130 ccm to 180 ccm . Accordingly, the refrigerant capacity thus had to be reduced slightly. As the capacity specification on the label has not yet been changed, proceed as follows: On vehicles manufactured up to the vehicle identification number mentioned, check whether the refrigerant oil has already been topped up during a previous workshop visit. If not, add 50 ccm of refrigerant oil to the refrigerant circuit. Then correspondingly alter the refrigerant capacity specified on the label in waterproof ink and fill the refrigerant circuit with the specified quantity of refrigerant. Finally make a record of the change made in the vehicle data. On vehicles manufactured as of the vehicle identification number mentioned, check the refrigerant capacity specified on the label, alter accordingly in waterproof ink if applicable and then fill the refrigerant circuit with the specified quantity of refrigerant. |
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| Vehicles with an 8-cyl. TDI engine up to vehicle identification number 4H_ BN 018845 were filled at the factory with the same quantity of refrigeration oil as for the other engines. As of vehicle identification number 4H_ 018846, the refrigerant circuit on vehicles with an 8-cyl. TDI engine is filled at the factory with a larger quantity of refrigeration oil. This quantity of refrigeration oil applies retroactively to all vehicles with an 8-cyl. TDI engine. If the refrigerant circuit is re-charged on vehicles with an 8-cyl. TDI engine or the air conditioner compressor is replaced for example after cleaning the refrigerant circuit, the quantity of refrigeration oil in the refrigerant circuit is to be checked and topped up if necessary or the correct quantity must be added (e.g. at open pipes or component connections or by way of the air conditioner service station prior to filling with refrigerant). If the air conditioner compressor is replaced without having to clean the refrigerant circuit, the quantity of refrigeration oil in the new air conditioner compressor to be fitted should be adjusted in line with the quantity of oil poured out of the old air conditioner compressor (and topped up accordingly if necessary on vehicles up to the vehicle identification number specified above) → Chapter. |
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| The different oil quantities in the air conditioner compressor may result from the design of the air conditioner compressor (with or without oil separator at high-pressure connection) or, in the case of identical air conditioner compressors, from the design of the refrigerant circuit. Attention is to be paid to these oil quantities. Too much oil in the circuit results in higher pressures and a reduced cooling output of the system. Too little oil may lead to lubrication problems in the air conditioner compressor. |
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| As replacement air conditioner compressors are supplied with different oil capacities, the exact part no. must be heeded → Electronic parts catalogue. |
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| Too much oil in the circuit results in higher pressures and reduced air conditioner cooling output. Too little oil may lead to lubrication problems in the air conditioner compressor. The specified refrigerant oil quantities are therefore to be heeded. |
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| The air conditioner compressor may have been fitted at the factory with a rating plate indicating the part number and the quantity of refrigerant oil in the air conditioner compressor. |
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| At the start of production, all vehicles except the Audi A8 hybrid were fitted with mechanically driven air conditioner compressors manufactured by „Denso“. Air conditioner compressors produced by other manufacturers may also be fitted at a later date → Electronic parts catalogue and → Air conditioning; Rep. gr.87 (vehicle-specific Workshop Manual). |
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| At the start of production, the Audi A8 hybrid is fitted with an electrically driven „Denso“ air conditioner compressor (electrical air conditioner compressor -V470- with control unit for air conditioning compressor -J842-). There is no provision for an air conditioner compressor regulating valve -N280- on this air conditioner compressor. |
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| At the start of production, the Audi A8 hybrid was fitted with an air conditioner compressor with a refrigerant oil quantity of 200 ccm. Shortly after the start of production, the refrigerant oil quantity was reduced to 160 ccm. The refrigerant oil does not have to be reduced on vehicles fitted with an air conditioner compressor with a refrigerant oil quantity of 200 ccm. However, if the refrigerant circuit has been flushed for example, a total of 160 ccm should also be filled in in this vehicle as the specified refrigerant oil quantity. The correct amount of refrigerant oil will already be filled into a replacement air conditioner compressor → Electronic parts catalogue. |
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Caution