6. Functional Tests
6.1 General
This section describes the on-vehicle and off-vehicle
testing of the air heater to check its proper operation.
WARNING
The air heater shall not be operated in enclosed areas
like garages or workshops not provided with exhaust
venting facilities.
6.2 Adjustments
6.2.1 Adjustment of the CO
2
Contents
6.2.1.1 General
The CO
2
contents of the exhaust is adjusted with the
potentiometer on the control circuit board. The air heater
is preset by the manufacturer with respect to the com-
bustion and heating air fan fitted. After adjustment by the
manufacturer the potentiometer is in center position
(Fig. 601). After an inadvertent loss of this position it is
sufficient to restore its original position.
The manufacturer setting may be corrected by rotating
the potentiometer. A suitable tool like a small screw
driver (2.5 mm tip) is to be used.
CAUTION
Set potentiometer slowly; observe end positions.
Adjustment may be performed at any electrical system
voltage.
Clockwise rotation increases the fan speed and de-
creases the CO
2
contents. Counterclockwise rotation de-
creases the fan speed and increases the CO
2
contents.
If the setting range is not sufficient (e.g. after replace-
ment of the combustion and heating air fan) the manufac-
turer’s setting may be cancelled according to the
procedure described in the following.
6.2.1.2 New Basic Setting
CAUTION
The manufacturer’s setting cannot be restored.
1. Withdraw cover from upper shell according to 9.2.1.
2. Switch on air heater.
3. Rotate potentiometer two times and with no interrupt
through its complete setting range (e.g. max. - min.-
max.).
4. Adjust desired CO
2
contents (Fig. 601).
5. Switch off air heater.
6. Install cover and secure.
601
Fig. 601 Adjustment of CO
2
Contents
CO
2
+ –
Air Top 2000 S
6 Functional Tests
