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76
Heater/AC
Operating and display unit E87.
The redesigned system is based on the
performance data for top of the medium
range vehicles, taking account of low system
weight and energy consumption as well as, to
an increasing extent, recycling capability.
The operating and display unit E87 is
connected to the convenience CAN bus.
Diagnosis takes place via the K-wire.
Design and function
The air conditioner represents a further devel-
opment of the two-zone air conditioning
concept previously used in the A6.
Innovations include:
– Individual temperature control for both
driver and front passenger
– Option of synchronising the temperature
zones for driver and front passenger by
pressing the ”Auto” button for approx.
three seconds.
Example:
If the same temperature is desired for the
passenger’s side as for the driver’s side,
the ”Auto” button should be pressed for at
least three seconds.
The same applies the other way round, for
making the driver’s side temperature the
same as that of the passenger’s side.
– The fault diagnosis and measured value
blocks for the seat heating system are read
out via address word 08 for the air condi-
tioner.
– The system is encoded automatically via
the dash panel insert.– Integrated rotary control knob with poten-
tiometer for seat heating.
(this means the potentiometers cannot be
replaced individually)
– Intake blower V42 for passenger compart-
ment temperature sensor G56 is integrated
and cannot be replaced individually.
A distinction is made between eight different
versions, identified by means of the part
number index:
– with or without seat heating
– with or without navigation system,
– at a later date, with or without air quality
sensor.
SSP254_032
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81
Fresh air blower
Control technology has been integrated in the
new fresh air blower.
It includes the following features:
– Integrated control unit with diagnostic
capability via the operating and display
unit E87 (fault memory and measured
value block diagnosis-capable control
unit),
– optimised bearings for smoother running,
– separate solar input.
The required blower speed is calculated in the
operating and display unit E87, and requested
by the control unit for fresh air blower J126
via a PWM signal.In the case of malfunctions, such as e.g. a stiff
or blocked blower, this is signalled to the
operating and display unit E87 by duty cycle
changes based on the altered frequency. The
relevant fault is set.
The blower bearings have been re-engineered
in order to optimise the effectiveness of the
system.
This particularly benefits solar operation.
The energy supplied by the solar roof is
utilised to drive the fresh air blower by means
of special electronics via the separate solar
input in the blower.
SSP254_037
