Climate Control - Mercedes-Benz 212 Sedan E-Class Service Manual

Climate control

Climate control systems
Two climate control systems are available for model
series 212:
• THERMATIC two-zone automatic air conditioning
• THERMOTRONIC three-zone comfort automatic air
conditioning (with code (581))
Both climate control systems combine automatic
heating, ventilation and cooling systems.
With the two-zone automatic air conditioning the
temperature for the driver and front passenger sides
can be regulated independently. With the three-zone
comfort automatic air conditioning the rear AC oper-
ating unit can be used to set the temperature for the
rear passenger compartment separately. Further-
more, the center console contains a compact addi-
tional fan installed underneath the stowage compart-
ments. This fan can be used to regulate the air volume
for the front and rear zones separately via the control
buttons on the rear AC operating unit.
Both systems feature air recirculation and a combina-
tion filter with fine filtration function as standard.
The main improvements to the climate control
systems in model series 212 are:
• The passenger compartment ventilation with
regard to draft-free ventilation, low noise
emissions and effectiveness
• The design and layout of the operating units with
regard to clarity, ergonomic handling and harmoni-
zation with the interior styling
• The response behavior of the system functions
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Introduction of the New E-Class, Model Series 212 Sedan
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– This printout will not be recorded by the update service. Status: 01 / 2009 –
Control and sensor systems
The automatic function allows the air flow, air distribu-
tion and interior temperature to be regulated automat-
ically.
The actual values of the interior temperatures are
sensed by one ventilated sensor in the overhead
control panel, one near the ignition lock and also by
two air outlet temperature sensors on each side in the
air stream of the side and footwell vents. Depending
on various parameters such as the outside tempera-
ture, the coolant temperature and the values of the
above sensors, the appropriate target outlet tempera-
ture is calculated. If significant deviations are found,
the temperature is additionally corrected.
The standard-equipment sun sensor on the instrument
panel near the windshield is a dual sensor that regis-
ters the intensity and angle of incidence of sunlight on
the vehicle. According to the intensity, the registered
values are also used for the control loops of the
climate control. If the sunlight falls on one side only,
an appropriate temperature difference is set between
the left and right target temperatures.
The three-zone comfort automatic air conditioning
includes a pollutant sensor for calculating the
pollutant concentration; the values measured are
used to close the fresh air flap and shut off the outside
air supply completely if necessary.
A dew point sensor in this variant allows the refrig-
erant compressor to be controlled specifically
according to requirements.