Audi Workshop Service and Repair Manuals > A4 Mk3 > Heating, ventilation, air conditioning system | Air conditioning | Air conditioner | Components for control and regulation of air conditioner located in passenger compartment | Removing and installing air conditioner operating and display unit, Climatronic control unitJ255 | Assignment of air conditioner operating and display unit, Climatronic control unitJ255

Removing and installing air conditioner operating and display unit > < Removing and installing air conditioner operating and display unit, Climatronic control unitJ255

Assignment of air conditioner operating and display unit, Climatronic control unitJ255

Assignment of air conditioner operating and display unit, Climatronic control unit -J255-

t	As of 08.2007, „Deluxe“ air conditioning units with an air distribution housing with optimised air routing were gradually introduced (distinguishing features of versions „1“ and „2“ → Chapter and → Electronic parts catalogue).

t	Actuation of the coolant circulation pump -V50- (coolant pump -V36-) differs depending on the production period.

Note

The design of the coolant circulation pump -V50- (coolant pump -V36-) and pump actuation differ depending on the vehicle model and production period. As of Model Year 2012 and depending on the engine, the pumps fitted as of the start of production and actuated by way of a 500 hertz signal (500 pulses per second) are gradually being replaced by pumps actuated by way of a 100 hertz signal. The pumps actuated by way of a 100 hertz signal additionally feature a diagnostic function and are generally actuated by way of the corresponding engine control unit. Attention is therefore to be paid to correct assignment (only the assigned pump can ever be actuated) → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Current flow diagrams, Electrical fault finding and Fitting locations and → Electronic parts catalogue.

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Vehicles with a type „2“ air conditioning unit are only to be fitted with air conditioner operating and display units, Climatronic control unit -J255- of the „Deluxe“ type with part number „8T1 820 043“ as of index „Q“ (for left-hand drive vehicles) or part number „8T2 820 043“ as of index „M“ (for right-hand drive vehicles).

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If vehicles with a type „1“ air conditioning unit are fitted with an air conditioner operating and display unit, Climatronic control unit -J255- of the „Deluxe“ type with part number „8T1 820 043“ as of index „Q“ (for left-hand drive vehicles) or with part number „8T2 820 043“ as of index „M“ (for right-hand drive vehicles), the adaption is to be altered accordingly → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

Note

t	The different versions of the air conditioning units can be distinguished from the outside by the part number -B- on the sticker -A- → Electronic parts catalogue.

t	The part number -B- on the sticker -A- can be read for example with the CD changer removed (depending on vehicle equipment) → Electrical system; Rep. gr.90.

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Air conditioner operating and display units, Climatronic control unit -J255- of the „Deluxe“ type with part number „8T1 820 043“ up to index „L“ (for left-hand drive vehicles) or part number „8T2 820 043“ up to index „H“ (for right-hand drive vehicles) are not to be fitted with the type „2“ air conditioning unit.

Note

No modifications have been made to the air conditioning unit and the air distribution housing of the air conditioner „Basic“ version.

The Audi A5 Coupé and the Audi A4 as of Model Year 2009 are gradually being fitted with operating and display units, Climatronic control unit -J255- with part number 8T1 820 043 as of index „T“ (for left-hand drive vehicles) or 8T2 820 043 as of index „Q“ (for right-hand drive vehicles). These were fitted right from the start of production on the Audi Q5 → Electronic parts catalogue.

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On vehicles with such operating and display units and depending on the encoding and adaption, the screen display for example of the „MMI“ (Multi Media Interface) is no longer switched to „Air conditioning“ on pressing the buttons and actuating the controls of the operating and display unit. The air conditioner functions selected are then indicated as part of the current display → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Operating instructions for „Infotainment / MMI“ and → Owner's manual.

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Pay attention to correct assignment, encoding and adaption of the operating and display unit, Climatronic control unit -J255- for the control unit for front display and information control panel -J523- / the control unit 1 for information electronics -J794- → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051. In the event of incorrect assignment, encoding or adaption, the various air conditioner functions cannot be indicated in the MMI display and thus selected.

Note

t	Operating and display units, -J255- with part number 8T1 820 043 up to index „S“ (for left-hand drive vehicles) or 8T2 820 043 up to index „P“ (for right-hand drive vehicles) are installed on vehicles with a control unit for front display and information control panel -J523-.

Operating and display units, -J255- with part number 8T1 820 043 as of index „T“ (for left-hand drive vehicles) or 8T2 820 043 as of index „Q“ (for right-hand drive vehicles) may be fitted on vehicles with a control unit 1 for information electronics -J794- and a control unit 1 for information electronics -J794-. The various functions can only be displayed and thus selected if encoding and adaption have been performed correctly for the vehicle equipment.

t	As of Model Year 2010 a start/stop system will be available as an optional extra for this vehicle in conjunction with certain engines.

t	In Model Year 2010 petrol engines designed for operation with bioethanol are gradually being introduced (Flex Fuel Vehicle)

Note

On vehicles with start/stop system, the stop function may be inhibited depending on the setting on the operating and display unit, Climatronic control unit -J255-. If „Defrost“ mode has been set for example, no stop function is possible or the stop function is terminated and the engine started as soon as this mode is selected. This also applies if the difference between the set specified temperature and the measured actual temperature exceeds a certain value in heating and cooling mode → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

Vehicles with a start-stop system are only to be fitted with an operating and display unit, Climatronic control unit -J255- with part number 8T1 820 043 as of index „AG“ (for left-hand drive vehicles) or 8T2 820 043 as of index „AD“ (for right-hand drive vehicles) or with part number 8K_ 820 043 → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

If fitted, actuation of the coolant circulation pump -V50- (coolant pump -V36-) depends on the production period and the vehicle model. Attention is therefore to be paid to the correct -J255- version. In the case of -J255- with part number 8T1 820 043 as of index „AG“ (for left-hand drive vehicles) or 8T2 820 043 as of index „AD“ (for right-hand drive vehicles), attention is also to be paid to the adaption for actuation of -V50- (-V36-) → Chapter and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

In Model Year 2010, petrol engines designed for operation with bioethanol are being gradually introduced (Flex Fuel Vehicle). These engines are currently also fitted with a supplementary air heater element -Z35- → Chapter. On vehicles with a petrol engine, the electric supplementary heating (supplementary air heater element -Z35-) is actuated by a signal from the operating and display unit, Climatronic control unit -J255- by way of the local data bus (via the same output by which the fresh air blower control unit -J126- is actuated) to the supplementary air heater control unit -J604-. → Current flow diagrams, Electrical fault finding and Fitting locations.

Vehicles with a petrol engine designed for operation with bioethanol are only to be fitted with an operating and display unit, Climatronic control unit -J255- with part number 8T1 820 043 as of index „AG“ (for left-hand drive vehicles) or 8T2 820 043 as of index „AD“ (for right-hand drive vehicles) or with part number 8K_ 820 043 → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

t	Vehicles with a high-voltage system (hybrid vehicles)

Note

Vehicles with a high-voltage system (until conversion of the vehicle design, applicable only to left-hand drive vehicles) are only to be fitted prior to conversion of the design (as of Model Year 2012, see below) with an operating and display unit, Climatronic control unit -J255- with part number 8R1 820 043 → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051

An operating and display unit, Climatronic control unit -J255- with part number 8R1 820 043 is only to be fitted on vehicles with a high-voltage system until conversion of the vehicle design (as of Model Year 2012, see below). Following conversion of the vehicle design, vehicles with a high-voltage system will be fitted with operating and display units, Climatronic control unit -J255- with part number 8K_ 820 043 (pay attention to index of part number and encoding) → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051

To permit implementation of the various functions required for vehicles with a high-voltage system by the operating and display unit, Climatronic control unit -J255- following conversion of the design, such vehicles are only to be fitted with a -J255- provided with these functions. The functions required for vehicles with a high-voltage system for example are not available with a -J255- with part number 8K_ 820 043 and index „K or AA“ up to index „P or AE“. These functions are integrated into a -J255- with part number 8K_ 820 043 as of index „Q or AF“. Instead of a -J255- with part number 8Kx 820 043 and index „Q“, the version with index „AF“ for example can be fitted (use is not made of the -N25- actuation function provided) → Electronic parts catalogue. In this case, the functions required for the vehicle concerned are deactivated or activated by way of the encoding of -J255- → Vehicle diagnostic, testing and information systemVAS 5051/, ”Guided fault-finding” function.

t	As of Model Year 2012, modified -J255- are to be gradually introduced (introduction depending on model and version). Pay attention to the correct assignment → Electronic parts catalogue.

Note

As of Model Year 2012, the design of the vehicles is gradually to be converted, starting with the Audi A4 and Audi A5. Vehicles manufactured prior to conversion are only to be fitted with an operating and display unit, Climatronic control unit -J255- with part number 8T__ 820 043 (the versions with part number 8R1 820 043 only on vehicles with a high-voltage system). Vehicles manufactured following conversion are only to be fitted with an operating and display unit, Climatronic control unit -J255- with part number 8K_ 820 043 → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051

On the „Deluxe“ version of the air conditioner, the -J255- with part number 8T_ 820 043 (with part number 8R1 820 043) -A- and with part number 8K_ 820 043 -B- can be distinguished (when fitted) as follows: On the -J255--A- (part number 8T_ 820 043 / 8R1 820 043) fitted from the start of production onwards, the seat heating and the seat ventilation are selected using the buttons -C- and the rotary pushbuttons. On the -J255--B- (part number 8K_ 820 043) fitted as of conversion of the vehicle design (gradual introduction as of Model Year 2012), the seat heating and seat ventilation are actuated by way of 2 separate buttons -D- and -E-. Furthermore, the arrangement of certain buttons -F- and -G- is different on the two versions.

t	On introduction of the -J255- of type -B-, the seat heating and seat ventilation can be set separately in 3 stages by way of the corresponding buttons → Owner's manual.

With the air conditioner „Basic“ version fitted, the -J255- with part number 8T_ 820 043 (with part number 8R1 820 043) -A-) and with part number 8K_ 820 043 -B- can be distinguished as follows for example: When fitted, the two versions -A- and -B- can only be distinguished from the rotary pushbutton control (version -B- with a chrome ring) and the seat heating buttons. On the -J255--A- fitted as of the start of production, the seat symbols in the buttons -C- and -D- face in different directions. On the -J255--B- fitted as of conversion of the vehicle design (gradual introduction as of Model Year 2012), the seat symbols in the buttons -C- and -D- face in the same direction.

t	On introduction of the -J255- of type -B-, the seat heating can be set in 3 stages by way of the corresponding buttons → Owner's manual.

As of Model Year 2012 and depending on the vehicle model, modified fresh air blower control units -J126-, fresh air blowers -V2-, air conditioner operating and display units, Climatronic control unit -J255-, onboard supply control units -J519-, convenience system central control units -J393-, air quality sensors -G238- and air conditioning units are gradually to be introduced. Pay attention to the correct version and assignment of these components → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

t	At the start of production, the humidity sender -G355- was only fitted with air conditioners of the „Deluxe“ type. Since the introduction of the start-stop system as of Model Year 2010, -G355- is also fitted on vehicles with an air conditioner of the „Basic“ type and this optional extra.

On vehicles manufactured prior to design conversion (except the Audi Q5 Hybrid), the measured value of -G355- is evaluated by the convenience system central control unit -J393- or the data bus diagnostic interface -J533-. On vehicles manufactured as of product conversion (and on all Audi Q5 Hybrid models), the measured value of -G355- is evaluated by the onboard supply control unit -J519- → Current flow diagrams, Electrical fault finding and Fitting locations, → Electrical system and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

t	The different versions of the air conditioning units can be distinguished from the outside by the part number -B- on the sticker -A- → Electronic parts catalogue.

t	The part number -B- on the sticker -A- can be read for example with the CD changer removed (depending on vehicle equipment) → Electrical system; Rep. gr.90.

As of Model Year 2012 and depending on the vehicle model, engine and production period, different versions of the coolant circulation pump -V50- (coolant pump -V36-) are gradually to be introduced. Actuation of these pumps also differs. As of Model Year 2012, the pumps fitted as of the start of production and actuated by way of a 500 hertz signal (500 pulses per second) are being replaced by pumps actuated by way of a 100 hertz signal. The pumps actuated by way of a 100 hertz signal additionally feature a diagnostic function and are generally actuated by way of the corresponding engine control unit. Attention is therefore to be paid to correct assignment (only the assigned pump can ever be actuated) → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051, → Current flow diagrams, Electrical fault finding and Fitting locations and → Electronic parts catalogue.

t	As of Model Year 2012, certain vehicles with a 4-cyl. engine are gradually to be fitted with an air conditioner compressor additionally provided with an air conditioning system magnetic clutch -N25-.

Note

In certain air conditioner operating modes (e.g. „Econ“ mode), the air conditioner compressor drive system is completely deactivated by way of this magnetic clutch. For -N25- to be actuated by the operating and display unit, Climatronic control unit -J255-, the correct version of -J255- must be fitted and correctly encoded → Electronic parts catalogue and → Vehicle diagnostic, testing and information systemVAS 5051/, ”Guided fault-finding” function.

To permit actuation of the air conditioning system magnetic clutch -N25- by the operating and display unit, Climatronic control unit -J255-, these vehicles are only to be fitted with a -J255- provided with the functions required for actuation of -N25- (a -J255- with part number 8K_ 820 043 and index „K“ is not designed for actuation of -N25- for example. A -J255- with part number 8K_ 820 043 and index „AA“ is designed for actuation of -N25- for example). Instead of a -J255- with part number 8K_ 820 043 and index „K“, a version with index „AA“ (use is not made of the -N25- actuation function provided) or a version with index „AF“ (use is not made of the functions for actuation of -N25- or for vehicles with a high-voltage system) can also be fitted → Electronic parts catalogue. In this case, the functions required for the vehicle concerned are deactivated or activated by way of the encoding of -J255- → Vehicle diagnostic, testing and information systemVAS 5051/, ”Guided fault-finding” function.

Heating, ventilation, air conditioning system
Air conditioning / Air conditioner
Components for control and regulation of air conditioner located in passenger compartment / moving_and_installing_air_conditioner_operating_and_display_unit_climatronic_control_unitj255/">Removing and installing air conditioner operating and display unit, Climatronic control unitJ255
Assignment of air conditioner operating and display unit, Climatronic control unitJ255

Removing and installing air conditioner operating and display unit > < Removing and installing air conditioner operating and display unit, Climatronic control unitJ255