Alfa Romeo 156 Owner's Manual page 117

To ensure correct opera-
tion of the incipient misting
sensor, stickers (e.g. road
licence holder) must not be applied
in the "control" area between the
sensor and the windscreen. For this
very reason, both the sensor and
the windscreen must always be
kept clean, to avoid accumulation
of dirt or other substances.
116
WARNING The demisting procedure is
enabled every time the ignition key is turned
to MAR, or pressing the
AUTO
When this procedure is working it can be
turned off pressing one of the following but-
tons: compressor, air recirculation, air dis-
tribution, air flow. This operation inhibits the
incipient misting sensor signal until the
button is pressed again or the next time the
ignition key is turned to MAR.
On certain versions, the system is inte-
grated by an anti-pollution sensor that is able
to switch on the inside air recirculation func-
tion automatically, to reduce the unpleasant
smell of polluted air when driving in urban
areas, queues, tunnels, and when the wind-
screen wash/wiper is operated (with the
typical smell of spirits).
WARNING The function of the anti-pol-
lution sensor is subordinate to safety con-
button. ditions; therefore disabling the climate con-
trol compressor or at an outside temperature
below 4°C, the sensor is disabled. In any
case, the sensor can be re-enabled press-
ing the recirculation button v until taking
it to the automatic mode.
AUTO
The anti-pollution sensor
is placed in the air flow in
front of the combined par-
ticle activated carbon filter and,
therefore, must be protected
against possible compressed air
jets produced by cleaning equip-
ment. Moreover, the water col-
lected from the windscreen wipers
should not come into contact with
the sensor: otherwise, the internal
air recirculation function could be
disabled for long periods.