Fault AUDI A6 ALLROAD 1999 C5 / 2.G Pneumatic Suspension System

47
The air dryer
The air must be dehumidiÞed in order to
prevent condensate and the associated
problems of corrosion and freezing. The
system used here is a so-called regenerative
air dryer system. A synthetically
manufactured silicate granulate is used as the
drying agent. This granulate can, depending
on the temperature, store up to 20% of its
own weight in water.
As the air dryer operates regeneratively, and
is only operated with oil-free, Þltered air, it is
not subject to replacement intervals and is
therefore maintenance-free.Because the air dryer is regenerated
only with waste air, the compressor
cannot be used to Þll any other
components. As this compressed air is
not fed back via the air dryer, no
regeneration can take place. For this
reason, the manufacturers do not Þt a
pressure connection for external
components.
Water/moisture in the system indicates
a fault in the air dryer or the system.
242_056 Granulate Þlling

61
Overheating protection
In order to protect the compressor from
overheating, it switches off at excess
temperatures.
A temperature module is integrated into the
control unit. This monitors the temperature
and is used to calculate the compressor
temperature.
The calculations are based on the running
and cooling times of the compressor.
The max. running time is limited to 120 sec.
(an fault entry is made in the control unit
whenever the maximum running time is
exceeded).
15 seconds running time are allowed
following every 6 minutes of cooling time.
After 48 minutes of cooling time the
maximum running time of 120 seconds is
available.
242_011
Battery protection
In order to protect the battery, the maximum
running time of the compressor is limited to
60 seconds after the ignition has been
switched ÒOFFÓ. The system switches off and
only reactivates after the ignition has been
switched ÒONÓ again.
Switching self-levelling on/off.
The system can be switched off using the
diagnostic tester, e.g. during repair work.
When the ignition is switched ÒONÓ, the
systemÕs off status is indicated by a ßashing
warning lamp (T34).
At a driving speed of >20 km/h the system is
activated automatically.
198_039242_085