Front Seat Heating And Ventilation

Components which participate in the control of the seat heating and seat ventilation

The Climatronic Control Module -J255- A/C display and control head sends the request to switch on the seat heating/seat ventilation vie the Data Bus system comfort to the respective control unit (the control unit depends on the vehicle version and vehicle equipment level using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for each control unit).

• On vehicles without a Memory Seat/Steering Column Adjustment Control Module -J136-, the Vehicle Electrical System Control Module -J519- directly controls the driver seat heating; the seat ventilation, where applicable, is controlled via the Left Front Seat Ventilation Control Module -J800- by the Vehicle Electrical System Control Module -J519- (different measured values block assignment in the Vehicle Electrical System Control Module -J519-).
• On vehicles without a Front Passenger Memory Seat Control Module -J521-, the Vehicle Electrical System Control Module -J519- directly controls the passenger seat heating; the seat ventilation, where applicable, is controlled via the Right Front Seat Ventilation Control Module -J799- by the Vehicle Electrical System Control Module -J519- (different measured values block assignment in the Vehicle Electrical System Control Module -J519-).
• On vehicles equipped with a driver seat with entry assist and/or memory function, the Memory Seat/Steering Column Adjustment Control Module -J136- directly controls the driver seat heating and seat ventilation, if applicable (different measured value block assignment in the Vehicle Electrical System Control Module -J519-).
• On vehicles with front passenger seat with power entry assist, the Front Passenger Memory Seat Control Module -J521- control the passenger seat heating.
• From MY 2010, this vehicle has a Start/Stop System for specific engines as optional equipment. If the vehicle has the Start/Stop System, the seat heating and ventilation can be switched off whenever the Stop function is active (to protect the Battery -A-). The setting for the heated seat control (and seat ventilation) remains stored in the Climatronic Control Module -J255- display and control head. After the engine is started again by the Start function, seat heating and ventilation is switched on again using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

• If there is a condition, where the heating or ventilation of the driver or front passenger seat cannot be switched on (for example due to a short circuit in the connection to a seat heater element or an interruption in the power supply to the respective control unit, etc.), this will be stored as a malfunction in the Vehicle Electrical System Control Module -J519-, in the Memory Seat/Steering Column Adjustment Control Module -J136- or in Front Passenger Seat Heating Control Module -J521- (depending on the vehicle type and the vehicle equipment level). Currently no information is sent to the Climatronic Control Module -J255- A/C display and control head via the Data Bus system; the DTC memory must be read out in each control unit or in the Comfort System Central Control Module -J393- using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. In the event of a complaint regarding seat heating or seat ventilation, first check the DTC memory of the control modules activating the seat heating and seat ventilation.
• The function test of the heated seats and seat ventilation control is described in the Guided Fault Finding for each control unit (Vehicle Electrical System Control Module -J519-, Memory Seat/Steering Column Adjustment Control Module -J136- or Front Passenger Memory Seat Control Module -J521-, depending on the vehicle version and vehicle equipment) using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.
• If, for example on the Vehicle Electrical System Control Module -J519- the measured current on terminal "30" falls below the value stored in the Vehicle Electrical System Control Module -J519-, the heated seat and seat ventilation output will be reduced or switched off completely in order to reduce the load on the Generator -C- using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.
• The measuring value block in the Climatronic Control Module -J255- A/C display and control head displays which setting for the seat heating or the seat ventilation has been selected. Depending on the version and equipment level of the vehicle, the seat heating and seat ventilation activation, the actual and specified seat temperature, the actual current flowing through the seat heating, etc. will appear in the individual control module (for example, inside measured values block for the Vehicle Electrical System Control Module -J519- using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.
• Depending on the vehicle version, the seat heating and ventilation for the front passenger seat can switch off after a certain period of time when it recognizes that the seat is empty. Refer to the Owner's Manual.
• There are different versions of the Climatronic Control Module -J255- A/C display and control head. The different versions can be recognized, for example, by the symbols on the buttons -A- (for vehicles equipped with "seat heating") and -B- (vehicles with "seat heating/seat ventilation")
  Fig 1: Identifying Climatronic Control Module

  Courtesy of AUDI OF AMERICA, LLC
• This illustration shows the Climatronic Control Module -J255- A/C display and control head in the "Convenience" version, as it was installed at the start of production.
• From MY 2012, as a running change (depending on the model and version), a revised Climatronic Control Module -J255- is being installed. Ensure the correct allocation.
• If installed, the recognizable differences on the "Convenience" system are, for example, the following: the seat heating and seat ventilation are selected via the buttons -C- and rotary adjuster on the Climatronic Control Module -J255- -A- installed from start of production. As a running change, vehicles from MY 2012 have two separate buttons -D- and -E- on the Climatronic control module -J255- -B- that operate the seat heating and the seat ventilation Also, the seat heating/seat ventilation on version -B- still have only 3 settings (contrary to the 6 setting on version -A-). A selected seat heating setting will be turned down one setting after a certain amount of time (refer to the Owner's Manual). The location of the buttons -F- and -G- is different between both versions.
  Fig 2: Identifying Climatronic Control Module Buttons

  Courtesy of AUDI OF AMERICA, LLC
• Both versions -A- and -B- are on the "Basis" when installed. Only the seat heating buttons are different (when installed, there are no noticeable differences on vehicles without seat heating). The seat symbols in the buttons -C- and -D- point in different directions on the Climatronic Control Module -J255- -A- installed from start of production. The seat symbols in buttons -C- and -D- face the same direction on the installed Climatronic Control Module -J255- -B- from MY 2012. The version -B- Climatronic Control Module -J255- has three seat heating settings (version -A- has six settings). The selected seat heating setting will be turned down one setting after a certain period of time (refer to the Owner's Manual).
  Fig 3: Identifying Seat Heating Buttons (2 Versions)

  Courtesy of AUDI OF AMERICA, LLC
• When the seat heating is on, the lamp in the button -A- or -B- "red" turns on and the selected seat heating setting appears in both the Climatronic Control Module -J255- -C- A/C display control head and the MMI display for a certain period of time on a Climatronic Control Module -J255- installed at start of production. On a Climatronic Control Module -J255- installed from MY 2012, the selected setting is displayed directly in the button when the indicator lamp turns on. The seat heating and seat ventilation can be selected separately on these versions. Refer to the Owner's Manual and Infotainment/MMI Owner's Manual. Therefore, ensure the correct allocation of the Climatronic Control Module -J255-.
  Fig 4: Identifying Seat Heating Buttons (From MY 2012)

  Courtesy of AUDI OF AMERICA, LLC
• The setting for the seat heating and ventilation is adjusted on the Climatronic Control Module -J255- A/C display and control head; this adjustment is transmitted to the Vehicle Electrical System Control Module -J519- via the Data Bus. The specified temperatures for the different seat heating and seat ventilation settings are stored in the Vehicle Electrical System Control Module -J519-. Depending on the version of the Vehicle Electrical System Control Module -J519- and on the production date of the vehicle, the specified temperature for the seat heating and ventilation can be different with the same setting on the Climatronic Control Module -J255- A/C display and control head using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for the Vehicle Electrical System Control Module -J519-).

Note the following when operating the seat ventilation:

• When the seat ventilation is turned on, the lamp in the button -B- turns on "blue" on a Climatronic Control Module -J255- installed from start of production. The setting for the seat ventilation also appears in the Climatronic Control Module -J255- -C- A/C display control head and in the MMI display for a certain period of time. As a running change, the selected setting is displayed directly in the seat ventilation button when the indicator lamp illuminates on a Climatronic Control Module -J255- installed from MY 2012. Refer to the Owner's Manual and Infotainment/MMI Owner's Manual
• The specified temperature for the seat depends on the selected seat ventilation setting (approximately 33 °C (91 °F) at setting 1 and approximately 18 °C (64 °F) at setting 6). If the actual temperature in the seat is less than the specified temperature, then the seat heating will be controlled until the specified temperature is reached using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for example, for the Vehicle Electrical System Control Module -J519-).
• Depending on seat temperature and selected setting of seat ventilation, seat heater can be switched on automatically by the control module. If necessary, only seat cushion is heated in seat ventilation mode, seat bolster heating not switched on. Refer to appropriate SYSTEM WIRING DIAGRAM.
• The blower activation for the seat cushion and seat backrest (2 blowers each in the seat backrest and seat cushion) depends on the seat ventilation setting (approximately 40% of the maximum output at setting 1, and approximately 85% at setting 6). If the temperature of the seat is below 15 °C (59 °F), the fans in the seat will not work. The fans for the seat and the backrest only work when the seat is warmer than 15 °C (59 °F) (the heating element heats the seat when the seat ventilation is on) using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for example, for the Vehicle Electrical System Control Module -J519-, the Memory Seat/Steering Column Adjustment Control Module -J136- and the Front Passenger Memory Seat Control Module -J521-, depending on the vehicle). Refer to FRONT SEATS and FRONT SEAT COVERS AND CUSHIONS (for the allocation of seat components).
• The seat heating activation depends on the version of the Climatronic Control Module -J255- installed (three- or six setting seat heating or seat ventilation) and on the selected seat heating setting and the measured value of the seat temperature sensor (in setting 1 up to approximately 18 °C (64 °F) and in setting 3 or 6 up to approximately 40/60 °C (104/140 °F)) using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. (for example, for the Vehicle Electrical System Control Module -J519-, the Memory Seat/Steering Column Adjustment Control Module -J136- and the Front Passenger Memory Seat Control Module -J521-, depending on the vehicle) . Refer to FRONT SEATS and FRONT SEAT COVERS AND CUSHIONS (for the allocation of seat components).
• In seat ventilation mode, the seat is heated up depending on the selected seat temperature setting and the measured seat temperature (measured value of the temperature sensor in the seat surface). Also, at a low seat temperature, the output of the blower fan installed in the seat can be reduced using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. (for example, for the Vehicle Electrical System Control Module -J519-, the Memory Seat/Steering Column Adjustment Control Module -J136- and the Front Passenger Memory Seat Control Module -J521-, depending on the vehicle).
• The activation of the seat ventilation is controlled by different control units depending on the vehicle version and equipment level. The Climatronic Control Module -J255- A/C display and control head sends the information to the respective control module via the selected seat ventilation setting and via the Convenience Data Bus system (depending on the version of the vehicle and the equipment level, it is sent to the Memory Seat/Steering Column Adjustment Control Module -J136-, the Passenger Memory Seat Control Module -J521- and the Vehicle Electrical System Control Module -J519-). Refer to appropriate SYSTEM WIRING DIAGRAM. The Memory Seat/Steering Column Adjustment Control Module -J136-, and the Passenger Memory Seat Control Module -J521- then directly activate, for example, the different blowers installed in the seats. Via a LIN Bus, the Vehicle Electrical System Control Module -J519- first activates the Right Front Seat Ventilation Control Module -J799- and if necessary, the Left Front Seat Ventilation Control Module -J800- (depending on the equipment level); and the Right Front Seat Ventilation Control Module -J799- and the Left Front Seat Ventilation Control Module -J800- (if necessary) then activate, for example, the different blowers installed in the seats. Refer to appropriate SYSTEM WIRING DIAGRAM and using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. For the Vehicle Electrical System Control Module -J519-, the Memory Seat/Steering Column Adjustment Control Module -J136- and the Front Passenger Memory Seat Control Module -J521-.