2003 AUDI A8 windscreen

Downloaded from www.Manualslib.com manuals search engine 59SSP282_063
Telephone/
telematics control
unit J526
Front information
display and operating
unit control unit J523Rear DVD changer
R162Telephone
handset
R37
Control unit for rear
left
information display
and operating
unit J648
DSP control unit
J525
Navigation system
control unit
J401
TV tuner
R78
Digital radio
R147
Radio module R Chip card reader
control unit
J676 CD changer
R41 CD ROM drive
R92 Data bus diagnostic
interface J533
Fresh-air blower
control unit
J126Heated windscreen
control unit J505Rear left footwell
heater element Z42Rear right footwell
heater element Z43Driver seat
ventilation
control unit J672Front passenger
seat ventilation
control unit J673

Parking aid control
unit J446 Entry and start
authorisation
control unit J518 Energy
management
control unit J644 Rear seat
adjustment with
memory control
unit J522 Climatronic control
unit J255
Trailer detector
control unit J345
Rear Climatronic
control and
display unit E265Tyre pressure
monitor control unit
J502
Sun roof electronics
control unit J528
Additional heater
control unit J364Driver identification
control unit J589
Auxiliary heating
radio controlled
receiver R64 Sliding sun roof
motor V1 Front passenger
side rear seat
ventilation
control unit J675 Driver side rear seat
ventilation control
unit J674 Control unit for rear
right
information display
and operating
unit J649
MOST busBluetooth
TM
LIN
LIN

Downloaded from www.Manualslib.com manuals search engine 72
An optional feature for the Audi A8 ´03 is
4-zone climate control, enabling both driver
and all passengers to make individual
settings independently of the climate control
level selected for the other occupants.
Design and operation
The air conditioning system represents a
more advanced version of the concept
employed in the Audi A8 predecessor model
with 2-zone climate control and features fully
automatic regulation.
Heating/Air Conditioner
The following components are new features
as compared to the systems previously fitted
in the Audi A8:
– Humidity sender G355
– Evaporator outflow temperature sender
G263
– Two versions: 2-zone front climate control
with 12 control motors and 4-zone front
and rear climate control with 15 control
motors
– Rear climate control with electric rear
additional heater as additional equipment
("4-zone system") – rear left and rear right
footwell heater element Z42 and Z43
– Second control and display unit with
4-zone climate control, Climatronic control
unit J255, rear Climatronic control and
display unit E265– Climate control menu in MMI (Multimedia
Interface) for display of climate control set
values and basic settings
– Front and rear seat heating and seat
ventilation
– Heated windscreen Z2
– Energy management control unit J644
The interaction of these components in
coordination with the entire air conditioning
system forms a control loop and permits
comfortable front and rear climate control to
suit all requirements.
SSP282_098

Downloaded from www.Manualslib.com manuals search engine 7374
A distinction is made between two air
conditioner unit versions
– 2-zone front and rear climate
control
– 4-zone front and rear climate
control
and three types of control and
display unit
– Air conditioner control panel with
no seat heating/ventilation
– Air conditioner control panel with
seat heating
– Air conditioner control panel with
seat heating and seat ventilation
(identified by part number index).
SSP282_099
Self-diagnosis
Fault diagnosis and measured value blocks
for air conditioner and seat heating system
can be read out by way of address words 08
"Air conditioner/heater electronics" and 28
"Rear climate control". The functions of and
exact procedure for self-diagnosis and
assisted fault-finding with VAS 5051 can be
found in the Heating/Air Conditioner
Workshop Manual for the relevant vehicle
model.
Operating principle
When the ignition is switched on, the
Climatronic control unit J255 starts up with
the same temperature, air distribution and
fresh-air blower speed settings etc. as were
applicable the last time the ignition was
switched off by way of the appropriate key or
using fingerprint recognition.
If fingerprint recognition has been
implemented, this has priority over key
recognition (refer also to SSP 287 – Audi A8 ´03
Electrical Components).
Personalised settings
The following settings can be made for each
climate control zone (front left, right and,
optionally, with 4-zone climate control rear left
and right):
– Left/right temperature
– Air flow
– Left/right air distribution
– Left/right seat heating
– Left/right seat ventilation
– Operating modes (AUTO for driver and front
passenger, temperature-adjustable centre
vents, automatically controlled
recirculated-air mode, ECON)
The heated windscreen can be activated by
way of the air conditioner defrost button or
the air conditioner control unit automatically
switches on the electric heated windscreen if
the appropriate conditions are satisfied
(windscreen defrost or automatic mode on
cold starting).
The Climatronic J255 and heated windscreen
J505 control units communicate by way of the
LIN bus. The Climatronic control unit transmits
the specified windscreen heating power to the
heated windscreen control unit on the LIN bus.
Heating/Air Conditioner
Key recognition takes place in the case of
remote control (radio or key transponder),
with the driver identification control unit
providing the Climatronic control unit J255
with the appropriate information by way of
the CAN bus.
The electrically heated windscreen is only
supplied with the amount of power which can
currently be drawn from the electrical system
without draining the battery. This is
monitored by the energy management
control unit J644.
As is the case with the Audi A4, the
windscreen is heated by applying voltage to a
metallic foil fitted in the glass (refer to
SSP 213).
As in the Audi A4, the air conditioner
compressor is regulated as a function of load
and controlled externally by way of the
compressor regulating valve (refer to
SSP 240). The Climatronic control unit J255 is
connected to the convenience CAN, via
which diagnosis is also performed.
A manual air conditioning system is not
available.

Downloaded from www.Manualslib.com manuals search engine Climatronic control unit J255
SSP282_100
Rear Climatronic control and display unit E265
Air conditioner basic setting
control
Heated rear window
control Front control panel
activation/
deactivation
Seat ventilation
control
Air distribution control
– Up
– Chest vent/centre
– Down Left rotary control/pushbutton
Rotary control +/- for
– Temperature
– Blower speed
– Air distribution up/down
– Seat heating
– Seat ventilation
– Menu control via MMI
Pushbutton
– Synchronisation of driver's
side, passenger's side and
rear settingsDriver's side
control panelPassenger's side
control panel Seat heating controlReset to basic setting/
automatic mode
Temperature sensor
with blowerAir conditioner defrost
and electrically heated
windscreen
Manual recirculated-air
mode control Blower control
Rear left
control panelCentre console/footwell
air distribution controlReset to basic setting/
automatic mode
Rear right
control panel
Left rotary control/pushbutton
Rotary control +/- for
– Temperature
– Chest vent and footwell air
distribution
– Seat heating
– Seat ventilation
Pushbutton
– Synchronisation of driver's
side and passenger's side
settings
Rear left seat heating
controlRear control panel
activation/
deactivation
Rear right seat
ventilation controlRear right seat heating
control
Rear left seat ventilation
control

Downloaded from www.Manualslib.com manuals search engine 76
Blower unit/air routing
As opposed to the predecessor model, the air
conditioner features an additional evaporator
outflow temperature sender G263. This is
installed in the air duct downstream of the
evaporator and constantly transmits the air
temperature downstream of the evaporator to
the Climatronic control unit J255.
If the left or right centre chest vent is closed
manually, the left/right centre vent control
motor V110/V111 is closed automatically by
the centre left/centre right G347/G348 vent
sensor signal.
Automatically controlled recirculated air
mode
Recirculated air mode is implemented
automatically for a certain period
– If the windscreen washer system switch is actuated or
– In the event of actuation by the air quality sensor G238
Heating/Air Conditioner
When replacing control motors, attention
must be paid to the assignment of the
flaps in the cam plate guides.
G150 Left vent temperature sender
G151 Right vent temperature sender
G263 Evaporator outflow temperature sender
V68
V71 Air-flow flap control motor
V102 Centre vent control motor
V107 Defroster flap control motor
V108 Left footwell flap control motor
V109 Right footwell flap control motor (not illustrated)
V113 Air-recirculation flap control motor
V199 Front right defroster/chest vent shutoff flap control motor
V200 Front left defroster/chest vent shutoff flap control motor
V218 Rear left vent control motor (4-zone system only)
V219 Rear right vent control motor (4-zone system only)Temperature flap control motor

Downloaded from www.Manualslib.com manuals search engine 80
Heating/Air Conditioner
SSP282_103 Fresh-air intake duct
temperature sensor G89
Flap control
motor potentiometers
G92, G113, G135, G136,
G137, G138, G139, G140,
G143, G317, G318, G349,
G350, G351, G352
Air quality sensor G238
Left/right vent temperature
sender G150/G151
Centre vent temperature
sender G191
Evaporator outflow temperature
sender G263
High-pressure sender G65
Sunlight penetration
photosensor G107
Solar cells in sunroof C20
System layoutControl unit with display
in dash panel insert J285
MOST busFront information display and
operating unit control unit J523
Rear right footwell heater
element Z43 Rear left footwell heater
element Z42 Fresh-air blower control unit
J126 with fresh-air blower V2Diagnosis CAN
Data bus diagnostic
interface J533
Sunroof electronics
control unit J528 Humidity
sender G355
Humidity sender
heater N340
Climatronic
control unit J255
Convenience CAN
Additional heater
control unit J364 Rear Climatronic control
and display unit E265Energy management
control unit J644Drive system CANEngine control unit J623Front information and display and
operating unit control unit J685
Radiator fan
control unit J293
Radiator fan V7
Air conditioning system compressor regulating valve N280
Flap control motors
V68, V71, V102, V107, V108, V109,
V110, V111, V113, V199, V200, V220,
V218, V219, V221
Coolant circulation pump V50
Left/right heat regulation valve N175/N176
Heated windscreen control unit J505
Heated windscreen Z2
Driver seat/front passenger seat ventilation control unit
J672/J673
Front left/front right heated seat Z45/Z46
Temperature sender for front left/front right seat
G344/G345

Downloaded from www.Manualslib.com manuals search engine 80
Heating/Air Conditioner
SSP282_103 Fresh-air intake duct
temperature sensor G89
Flap control
motor potentiometers
G92, G113, G135, G136,
G137, G138, G139, G140,
G143, G317, G318, G349,
G350, G351, G352
Air quality sensor G238
Left/right vent temperature
sender G150/G151
Centre vent temperature
sender G191
Evaporator outflow temperature
sender G263
High-pressure sender G65
Sunlight penetration
photosensor G107
Solar cells in sunroof C20
System layoutControl unit with display
in dash panel insert J285
MOST busFront information display and
operating unit control unit J523
Rear right footwell heater
element Z43 Rear left footwell heater
element Z42 Fresh-air blower control unit
J126 with fresh-air blower V2Diagnosis CAN
Data bus diagnostic
interface J533
Sunroof electronics
control unit J528 Humidity
sender G355
Humidity sender
heater N340
Climatronic
control unit J255
Convenience CAN
Additional heater
control unit J364 Rear Climatronic control
and display unit E265Energy management
control unit J644Drive system CANEngine control unit J623Front information and display and
operating unit control unit J685
Radiator fan
control unit J293
Radiator fan V7
Air conditioning system compressor regulating valve N280
Flap control motors
V68, V71, V102, V107, V108, V109,
V110, V111, V113, V199, V200, V220,
V218, V219, V221
Coolant circulation pump V50
Left/right heat regulation valve N175/N176
Heated windscreen control unit J505
Heated windscreen Z2
Driver seat/front passenger seat ventilation control unit
J672/J673
Front left/front right heated seat Z45/Z46
Temperature sender for front left/front right seat
G344/G345

Downloaded from www.Manualslib.com manuals search engine 82
Humidity sender G355
Heating/Air Conditioner
At low ambient temperatures, when the
windscreen is extremely cold, the top third is
particularly susceptible to fogging.
To cover this area, the humidity sender G355
is fitted in front of the base of the rear view
mirror.
The sender is designed to detect the
following:
– Humidity level
– Sender ambient temperature and
– Windscreen temperature
All three functions are combined in the
sender housing.
The humidity sender is intended for all
equipment versions.The sender data enable the air conditioning
system to detect potential misting of the
windscreen in good time.
Before water vapour from the air in the
passenger compartment can form on the
windows, the output of the air conditioner
compressor and the blower speed are
automatically increased and the defrost flap
is opened further. Dry air is then routed from
the open defrost vents to the windscreen and
side windows via the evaporator and heat
exchangers.
Measurement of humidity level and
corresponding temperature
Physical principles
Humidity measurement involves determining
the water vapour content of the passenger
compartment air. The capacity of air to
absorb water vapour is governed by the air
temperature. It is thus necessary to
determine not only the humidity level but also
the corresponding air temperature in the
measurement area.The warmer the air, the more water vapour it
can absorb. Water starts to condense if this
water-vapour enriched air cools down again.
This results in fine droplets forming on the
windscreen.
SSP282_104