coolant capacity AUDI A8 2003 D3 / 2.G Technical Features Manual

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Auxiliary heater/coolant additional heater
An auxiliary heater is available as an option
for all vehicle and engine versions. The
auxiliary heater with petrol engines and
additional heater with diesel engines are
integrated into the engine coolant circuit.
Vehicles with diesel engine are fitted with an
additional heater as standard. On diesel
engines with auxiliary heater, the activated
auxiliary heater is also used as engine
additional heater depending on temperature.
Heating/Air Conditioner
Design and operation are described in
SSP 240 – Audi A2 Technical Features.
Operation with cut-in by way of remote
control or timer
In the Audi A8 ´03, the auxiliary heater is
activated by the air conditioner. The heated
coolant is initially supplied to the passenger
compartment (primarily auxiliary heater
mode). On attaining pre-determined
temperature levels, engine pre-heating is
then switched in in line with a characteristic
curve.
Activation sequence:
1 A remote control or timer signal is
transmitted to the auxiliary heater control
unit.
2 The auxiliary heater then transmits a signal
via the CAN bus to the Climatronic control
unit J255.
3 The control unit then decides as a function
of desired temperature, ambient
temperature and passenger compartment
temperature whether auxiliary ventilation
or auxiliary heating is to be employed.
The setting of the auxiliary heater/
ventilation function is shown in the setup
menu in the MMI (Multimedia-Interface).The cut-in time is "programmed" by way of
the MMI system (Multimedia Interface) under
the menu item "timer status".
4.1 Auxiliary ventilation sequence
The energy management control unit
J644 interrogates the battery capacity
check function of the battery and energy
management system to determine
whether auxiliary ventilation can be
accepted. In the event of acceptance, the
fresh-air blower is actuated.