Electrical Checking Of Components Actuated By The Air Conditioner; Checking Of Heated Rear Window Z1 - Audi Air conditioning 2003 A8 Workshop Manual

7 Electrical checking of components
actuated by the air conditioner
By the front operating and display unit, Climatronic control unit -
J255- (and the rear Climatronic operating and display unit -
E265- )
7.1 Checking of heated rear window -Z1-
Note
Situations preventing activation of the heated rear window
♦
(short circuit in connection to rear window, open circuit in pow‐
er supply to front operating and display unit, Climatronic con‐
trol unit -J255- ) are stored as faults in the front operating and
display unit, Climatronic control unit -J255- ⇒ "Guided fault-
finding" function of vehicle diagnostic, testing and information
system VAS 5051.
If the voltage measured at the energy management control
♦
unit -J644- at terminal „30" drops below a value stored in the
energy management control unit -J644- , the rear window
heating is completely deactivated at present (or the power is
reduced) to relieve the load on the alternator (the electronics
system of the front operating and display unit, Climatronic
control unit -J255- reduces the actuation duty cycle from 100%
to 90....0%) ⇒ "Guided fault-finding" function of vehicle diag‐
nostic, testing and information system VAS 5051.
If the heated rear window has to be deactivated on account of
♦
undervoltage, the indicator lamp in the button for the heated
rear window in the front operating and display unit, Climatronic
control unit -J255- remains on. However if deactivation lasts
longer than approx. 150 s, the front operating and display unit,
Climatronic control unit -J255- switches off the indicator lamp.
The measured value block of the front operating and display
♦
unit, Climatronic control unit -J255- shows that the heated rear
window is being actuated or indicates why there is no actuation
in spite of a corresponding request ⇒ "Guided fault-finding"
function of vehicle diagnostic, testing and information system
VAS 5051.
Checking actuation of heated rear window operation is descri‐
♦
bed in the air conditioner guided fault-finding ⇒ "Guided fault-
finding" function of vehicle diagnostic, testing and information
system VAS 5051.
At ambient temperatures below 0 °C, the heated rear window
♦
remains switched on until the ignition is switched off (manual
deactivation is possible at any time). If the temperature during
a driving cycle rises above 0 °C, the heated rear window is
deactivated on completion of the operating period stored in the
front operating and display unit, Climatronic control unit -J255-
(approx. 10 minutes).
At ambient temperatures above 0 °C, the heated rear window
♦
is deactivated automatically on completion of the operating
period stored in the front operating and display unit, Clima‐
tronic control unit -J255- (approx. 10 minutes) by the front
operating and display unit, Climatronic control unit -J255- (on
vehicles with standard glass, for example, the actuation time
is governed by the encoding of the front operating and display
unit, Climatronic control unit -J255- ) ⇒ "Guided fault-finding"
function of vehicle diagnostic, testing and information system
VAS 5051.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

7. Electrical checking of components actuated by the air conditioner

Audi A8 2003 ➤
Air conditioning - Edition 09.2010
65