Overview - Display Control Heads, Vehicles With Automatic Climate Control System

"Convenience" A/C system version 

Courtesy of AUDI OF AMERICA, LLC

1. Front A/C Display Control Head 1 -E774-
   • Left regulator and button for seat heating (and neck heating)
   • Installed in the left instrument panel vent
   • Removing and Installing. Refer to LEFT KNOB FOR SEAT HEATING (AND NECK HEATING) ON Front A/C Display Control Head 1 -E774-, REMOVING AND INSTALLING .
   • Illuminated LEDs indicate the selected setting for the seat heating (and/or neck heating)
   • The selected setting can be set back one unit after a pre-set time
   • Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Climatronic Control Module -J255- and the Vehicle Electrical System Control Module -J519-.
   • For more information and description of the function. Refer to SEAT HEATING and the Owner's Manual.
     NOTE:

     The Front A/C Display Control Head 1 -E774- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the seat heating (and/or neck heating) according to the received requests.

     Only a place holder (a cover) that has no function is installed on vehicles without the optional "seat heating" or "seat and neck heating" equipment instead of the Front A/C Display Control Head 1 -E774-.

2. Front A/C Display Control Head 2 -E775-
   • Preset knob for the Fresh Air Blower -V2- speed
   • With the A/C  button to switch the A/C compressor activation on and off
   • Installed in the left center instrument panel vent (may be installed in the right center instrument panel vent on right-hand drive vehicles).
   • Removing and Installing. Refer to PRESET KNOB FOR FRESH AIR BLOWER SPEED (AND A/C SYSTEM OPERATION) ON Front A/C Display Control Head 2 -E775-, REMOVING AND INSTALLING .
   • Version for vehicles with an automatic climate control system.
   • Illuminated LED indicates the "A/C compressor on" function is selected
     NOTE:

     The Front A/C Display Control Head 2 -E775- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the various A/C system components according to the received requests.

     There are different versions on vehicles with a manual or an automatic climate control system. Ensure the correct version and allocation. Interchanging is not permitted.

     Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Vehicle Electrical System Control Module -J519-.

     Description of the function. Refer to the Owner's Manual.

3. Front A/C Display Control Head 3 -E776-
   • Preset knob for temperature and A/C system operation
   • Installed in the center instrument panel vent.
   • With Auto  button for automatic A/C system operation
   • Removing and Installing. Refer to PRESET KNOB FOR TEMPERATURE (AND A/C SYSTEM OPERATION) ON Front A/C Display Control Head 3 -E776-, REMOVING AND INSTALLING .
   • With the A/C  button to switch the A/C compressor activation on and off
   • Version for vehicles with an automatic climate control system.
   • There are different versions and functions depending on the A/C system version
   • Removing and Installing. Refer to PRESET KNOB FOR TEMPERATURE (AND A/C SYSTEM OPERATION) ON Front A/C Display Control Head 3 -E776-, REMOVING AND INSTALLING .
   • The Front A/C Display Control Head 3 -E776- transmits the selected temperature and desired A/C system operating mode to the Climatronic Control Module -J255-
   • The Front A/C Display Control Head 3 -E776- transmits the selected temperature and desired A/C system operating mode to the Climatronic Control Module -J255-
   • The preset temperature is shown in the installed display.
   • For vehicles with an auxiliary heater, it is activated depending on the selected temperature, coolant temperature, etc. if additional heating output is necessary to reach the desired temperature. Refer to PARKING/AUXILIARY HEATER OPERATION WITH DIESEL ENGINE .
     NOTE:

     The Front A/C Display Control Head 3 -E776- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the various A/C system components according to the received requests.

     There are different versions on vehicles with a manual or an automatic climate control system. Ensure the correct version and allocation. Interchanging is not permitted.

     Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for the Climatronic Control Module -J255-).

     Adjusting the temperature is only possible via the Front A/C Display Control Head 3 -E776- on the Audi TT. Both temperature control door motors (the Left Temperature Control Door Motor -V158- and the Right Temperature Control Door Motor -V159-) are activated together over their wide adjustment range by the Climatronic Control Module -J255- via the characteristic curves stored in the Climatronic Control Module -J255-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

     Description of the function. Refer to the Owner's Manual.

4. Front A/C Display Control Head 4 -E777-
   • Preset knob for air distribution and for manual recirculating air mode
   • Installed in the right center instrument panel vent (may be installed in the left center instrument panel vent on right-hand drive vehicles).
   • Version for vehicles with an automatic climate control system.
   • Removing and Installing. Refer to KNOB FOR AIR DISTRIBUTION ON Front A/C Display Control Head 4 -E777-, REMOVING AND INSTALLING .
     NOTE:

     The windshield, door window and rear window may fog up in recirculating air mode if the A/C system is switched off, for example (the air moisture in the vehicle interior increases and then condenses on the vehicle windows. The A/C system does not dehumidify the air).

     To defog the vehicle windows as quickly as possible, only restricted recirculating air mode is possible if the "defrost mode" function is activated via the Defrost Button -E782-. The Climatronic Control Module -J255- switches to fresh air mode and the A/C system operation is activated if possible (the A/C compressor is activated). The illumination of the indicator lamp in the Defrost Button -E782- indicates that the A/C system is switched on. If operating the A/C system is not desired in the "air to windshield" setting, it can be switched off again by pressing the A/C  button. Refer to the Owner's Manual.

     The Front A/C Display Control Head 4 -E777- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the various A/C system components according to the received requests.

     Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Vehicle Electrical System Control Module -J519-.

     Description of the function. Refer to the Owner's Manual.

     The "automatic recirculating air mode" function is activated when the Air Quality Sensor -G238- (assembled together with the Humidity Sensor in Fresh Air Intake Duct -G657- in one component) detects polluted surrounding air and automatic recirculating air mode is switched on via the Multimedia System Control Head -E380-. The selected or changed functions are shown in the instrument cluster center display. Refer to the Owner's Manual.

     The "automatic recirculating air mode" function is switched off when the "defrost mode" function is selected via the Defrost Button -E782-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. For additional information, refer to the Owner's Manual.

5. Defrost Button -E782-
   • Illuminated LED indicates the "defrost mode" function is selected.
   • The "recirculating air mode" function is canceled when selecting the "defrost mode" function (air to the windshield).
   • Removing and Installing. Refer to FRESH AIR AND Recirculating Air Mode Button -E781- /Defrost Button -E782-, REMOVING AND INSTALLING .
     NOTE:

     The Climatronic Control Module -J255- receives a signal from the Defrost Button -E782- when the "defrost mode button" is pressed. The Climatronic Control Module -J255- then switches the A/C system to fresh air mode if it is in recirculating air mode.

     The Defrost Button -E782- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the various A/C system components according to the received requests.

     Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Vehicle Electrical System Control Module -J519-.

     For more information and description of the function. Refer to the Owner's Manual.

6. Rear Window Defogger Button -E230-
   • Illuminated LEDs indicate the "Rear window defogger on" function is selected.
   • Version for vehicles with a manual climate control system.
   • The rear window defogger can stay switched on by pressing and holding the button
   • Removing and Installing. Refer to Rear Window Defogger Button -E230-, REMOVING AND INSTALLING .
     NOTE:

     The Rear Window Defogger Button -E230- sends a signal to the Climatronic Control Module -J255- when the button is pressed. Refer to the appropriate Wiring Diagram.

     The Climatronic Control Module -J255- then sends the information that the Rear Window Defogger Button -E230- was pressed to the Vehicle Electrical System Control Module -J519- via the Data Bus. The Vehicle Electrical System Control Module -J519- then switches the activation of the Rear Window Defogger -Z1- on or off (directly or via the Rear Window Defogger Relay -J9-, depending on equipment. Refer to the appropriate Wiring Diagram). The Climatronic Control Module -J255- switches the indicator lamp in the Rear Window Defogger Button -E230- on or off.

     Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Vehicle Electrical System Control Module -J519-.

     Description of the function. Refer to the Owner's Manual.

     The Rear Window Defogger -Z1- is activated by the Vehicle Electrical System Control Module -J519- (via the Rear Window Defogger Relay -J9-) only when the engine is running. If the engine is not running, there is no activation or response from the Vehicle Electrical System Control Module -J519-. The indicator lamp in the button does not illuminate or goes out again shortly after pressing it. Refer to the Owner's Manual and use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

     The Rear Window Defogger -Z1- is switched off automatically by the Vehicle Electrical System Control Module -J519- after the operating time stored in the Vehicle Electrical System Control Module -J519- (approximately 10 minutes) has elapsed when the exterior temperature is greater than 0 °C (32 °F), for example. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. Refer to the Owner's Manual.

     The Rear Window Defogger -Z1- stays switched on with outside temperatures less than 0 °C (32 °F) until the ignition is switched off (it can be switched on and off manually at any time). If the temperature becomes greater than 0 °C (32 °F) during a driving period, the Rear Window Defogger -Z1- is switched off after the operating time stored in the Vehicle Electrical System Control Module -J519- has elapsed (approximately 10 minutes). Refer to the Owner's Manual.

     If the rear window defogger button is pressed for a longer period of time when turning it on, the rear window defogger remains switched on until the button is pressed again or the ignition is switched off. Refer to the Owner's Manual.

     If the Vehicle Electrical System Control Module -J519- measured voltage at terminal "30" falls below a value stored in the Vehicle Electrical System Control Module -J519- (or in the Climatronic Control Module -J255-), the output is reduced or the rear window defogger switched off completely to reduce the load on the Generator -C-. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

     If the activation of the Rear Window Defogger -Z1- must be switched off briefly due to low voltage from the Vehicle Electrical System Control Module -J519-, the indicator lamp in the rear window defogger button remains switched on. However, if the deactivation lasts longer, the Vehicle Electrical System Control Module -J519- switches off the request to activate the indicator lamp in the button and the indicator lamp goes out.

     For vehicles with the Start/Stop System, the rear window defogger may be switched off to protect the Battery -A- when the Stop function is active. The setting for the Rear Window Defogger -Z1- activation remains stored. The rear window defogger is switched on again as soon as the engine is restarted via the Start function. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function (for the Vehicle Electrical System Control Module -J519-).

     The "Read measured values" function of the Guided Fault Finding  for the Vehicle Electrical System Control Module -J519- (the Climatronic Control Module -J255-) shows that the rear window defogger is switched on or why there is no activation even though there is a request. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

     Description of the activation function test for the rear window defogger using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Vehicle Electrical System Control Module -J519-.

7. Climatronic Control Module -J255-
   • Removing and Installing. Refer to Climatronic Control Module -J255-, REMOVING AND INSTALLING .
   • Version for vehicles with an automatic climate control system.
   • The Climatronic Control Module -J255- receives information from the various controls (control heads, regulators and buttons) via data wires or direct wire connections. Refer to the appropriate Wiring Diagram.
   • The A/C system regulation is controlled via the selected presets on the controls.
   • Certain presets on the controls are transmitted by the Climatronic Control Module -J255- to secondary control modules via the Data Bus (for example, the activation of the rear window defogger, the seat heating, etc. to the Vehicle Electrical System Control Module -J519-). The Vehicle Electrical System Control Module -J519- reports the change request back to the Climatronic Control Module -J255- and it then activates the indicator lamps in the controls. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function. Refer to the appropriate Wiring Diagram.
     NOTE:

     There are different versions of the Climatronic Control Module -J255- (for example, for vehicles with a manual or an automatic climate control system, etc.). Ensure the correct version and allocation.

     To check the activation function, use the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

     Function description of the various controls and buttons. Refer to the Owner's Manual.

     For vehicles with an auxiliary heater, it is activated depending on the selected temperature, coolant temperature, etc. if additional heating output is necessary to reach the desired temperature. Refer to PARKING/AUXILIARY HEATER OPERATION WITH DIESEL ENGINE .

     Installed on the left in right-hand drive vehicles.

8. Front A/C Display Control Head 5 -E778-
   • Right regulator and button for seat heating (and neck heating)
   • Installed in the right instrument panel vent
   • Removing and Installing. Refer to RIGHT KNOB FOR SEAT HEATING (AND NECK HEATING) ON Front A/C Display Control Head 5 -E778-, REMOVING AND INSTALLING .
   • Illuminated LEDs indicate the selected setting for the seat heating (and/or neck heating)
   • The selected setting can be set back one unit after a pre-set time
   • Check the activation function using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function for the Climatronic Control Module -J255- and the Vehicle Electrical System Control Module -J519-.
   • For more information and description of the function. Refer to SEAT HEATING and the Owner's Manual.
     NOTE:

     The Front A/C Display Control Head 5 -E778- exchanges information with the Climatronic Control Module -J255- via a "LIN Bus" data wire. The Climatronic Control Module -J255- activates the seat heating (and/or neck heating) according to the received requests.

     Only a place holder (a cover) that has no function is installed on vehicles without the optional "seat heating" or "seat and neck heating" equipment instead of the Front A/C Display Control Head 1 -E774-.