MERCEDES-BENZ R350 2008 W251 Owner's Manual

210 Controls in detail
Climate control
1Temperature control, left
2Air distribution and air volume
(automatic, manual)
3Front defroster
4Increasing air volume
5Air distribution (directs air through
the windshield and side air vents)
6Rear climate control* on/off
Air supply for rear passenger
compartment on/off
:USA only
<Canada only
7Temperature control, right
8AC cooling on/off
Residual heat/ventilation
9Air distribution (directs air through
center and side air vents)
aAir distribution (directs air through
the footwells and side air vents)
bAir volume display
cDecreasing air volume
dRear window defroster
eAir recirculation
fInterior temperature sensor
gClimate control on/off

211 Controls in detail
Climate control
The climate control is operational when-
ever the engine is running. You can oper-
ate the climate control system in either the
automatic or manual mode. The system
cools or heats the interior depending on
the selected interior temperature and the
current outside temperature.Nearly all dust particles, pollutants and
odors are filtered out before outside air en-
ters the passenger compartment through
the air distribution system.
The air conditioning will not engage (no
cooling) if the A/C mode is deactivated
(
page 219).
Warning!G
When operating the climate control, the air
that enters the passenger compartment
through the air vents can be very hot or very
cold (depending on the set temperature).
This may cause burns or frostbite to unpro-
tected skin in the immediate area of the air
vents.
Always keep sufficient distance between un-
protected parts of the body and the air
vents. If necessary, use the air distribution
controls (
page 210) to direct the air to air
vents in the vehicle interior that are not in
the immediate area of unprotected skin.
Warning!G
Severe conditions (e.g. strong air pollution)
may require replacement of the filter before
its scheduled replacement interval.
A clogged filter will reduce the air volume to
the interior and the windows could fog up,
impairing visibility and endangering you and
others. Have a clogged filter replaced as
soon as possible at an authorized
Mercedes-Benz Light Truck Center.
Warning!G
Follow the recommended settings for heat-
ing and cooling given on the following pag-
es. Otherwise the windows could fog up,
impairing visibility and endangering you and
others.
iIf the vehicle interior is hot, ventilate the in-
terior before driving off, see “Summer opening
feature” (
page 244). The climate control will
then adjust the interior temperature to the set
value much faster.
Keep the air intake grille in front of the wind-
shield free of snow and debris.

212 Controls in detail
Climate control
Deactivating the climate control
system
Deactivating
Press button´ (page 210).
The indicator lamp on the button
comes on.Reactivating
Press buttonU (page 210).
Operating the climate control system
in automatic modeActivating
Press buttonU (page 210) while
the engine is running.
The indicator lamp on the button
comes on. The air volume and air distri-
bution are adjusted automatically.
Use temperature controls1 and7
(
page 210) to separately adjust the
air temperature on each side of the
passenger compartment.
The interior air temperature is adjusted
automatically.
Warning!G
When the climate control system is
switched off, the outside air supply and cir-
culation are also switched off. Only choose
this setting for a short time. Otherwise the
windows could fog up, impairing visibility
and endangering you and others.
iYou can also press button´
(
page 210) on the climate control panel.
If you press button| (
page 210) to reacti-
vate the climate control system, the defrosting
mode is activated.
iWhen operating the climate control system
in automatic mode, you will only rarely need to
adjust the temperature, air volume and air distri-
bution.
In automatic mode, cooling with dehumidify is
switched on. This function can be switched off if
necessary (
page 219).
iThe settings for the passenger side are also
used for the rear passenger compartment.

213 Controls in detail
Climate control
Deactivating
Press button
orQ
(
page 210).
The indicator lamp on buttonU
goes out. The automatic operation of
air volume switches off. The selected
blower speed is shown in the air
volume displayb (
page 210).
or
Press air distribution button 5,9,
ora (
page 210).
The indicator lamp on buttonU
goes out. The automatic operation of
air distribution switches off.
Setting the temperature
Use temperature controls1 and7
(
page 210) to separately adjust the air
temperature on each side of the passenger
compartment. You should raise or lower
the temperature setting in small incre-
ments, preferably starting at 72°F (22°C).
The climate control will adjust to the set
temperature as fast as possible.
Increasing
Turn temperature control1and/or
7 (
page 210) slightly clockwise.
The climate control system will corre-
spondingly adjust the interior air
temperature.
Decreasing
Turn temperature control1 and/or
7 (
page 210) slightly counterclock-
wise.
The climate control system will corre-
spondingly adjust the interior air
temperature.
Adjusting air distribution
Press air distribution button5,9, ora
(
page 210) to adjust the air distribution.
The following symbols are found on the
buttons:
Press the desired air distribution
button5,9, ora (
page 210).
The indicator lamp on buttonU
goes out.
SymbolFunction
aDirects air through the center
and side air vents
ZDirects air to the windshield
and side air vents
YDirects air to the footwells and
side air vents

214 Controls in detail
Climate control
Adjusting air volume
Five blower speeds are available.
Press button
to decrease or
buttonQ to increase air volume
(
page 210) to the desired level.
The indicator lamp on buttonU
(
page 210) goes out. The automatic
operation of air volume switches off.
The selected blower speed is
shown in the air volume display b
(
page 210).
Adjusting air volume for the center and
side air vents
Opening the center air vents
Turn thumbwheels 6 and 7
(
page 208) upward.
The corresponding center air vents on
the left and right are open.Closing the center air vents
Turn thumbwheels 6 and 7
(
page 208) downward.
The corresponding center air vents on
the left and right are closed.
Opening the side air vents
Turn thumbwheels 3 and 8
(
page 208) upward.
The corresponding side air vents on the
left and right are open.
Closing the side air vents
Turn thumbwheels 3 and 8
(
page 208) downward.
The corresponding side air vents on the
left and right are closed.
Front defroster
You can use this setting to defrost the
windshield, for example if it is iced up. You
can also use it to defog the windshield and
door windows.
Activating
Press button| (page 210).
The indicator lamp on the button
comes on.
iKeep this setting selected only until the
windshield or the door windows are clear again.

215 Controls in detail
Climate control
The climate control switches to the follow-
ing functions automatically:

most efficient blower speed and
heating power, depending on outside
temperature

air flows onto the windshield and the
front door windows (side air vents must
be open)

the air conditioning compressor
switches on at outside temperatures
above approximately 41°F (5°C) for
air-dryingAdjustments
You can adjust the air volume and the tem-
perature when the front defroster is
switched on. The air flow will remain on the
windshield and front door windows.
Press button
to decrease or
buttonQ to increase air volume
(
page 210) to the desired level.
The air volume decreases/increases to
the next lower/higher blower speed
and heating switches to the tempera-
ture that was set before the front de-
froster was switched on.
The indicator lamp on button|
goes out. The indicator lamp on
button9 comes on.
or
Turn temperature
control1and/or7 (
page 210)
slightly in any direction.Heating switches to the temperature
that was set before the front defroster
was switched on.
The indicator lamp on button|
goes out. The indicator lamp on
button9 comes on.
iThe air conditioning compressor remains on
even if the indicator lamp in button| goes
out. This helps to prevent the windshield from
fogging.

216 Controls in detail
Climate control
Deactivating
Press button| (page 210) once
more.
The indicator lamp on the button goes
out. Defrosting is turned off.
The previous settings are in effect
again. The air conditioning compressor
remains switched on.
Windshield fogged on the outside
Switch the windshield wipers on
(
page 59).
Press button| (page 210).
The indicator lamp on the button
comes on.The climate control switches automatically
to the following functions:

most efficient blower speed and
heating power, depending on outside
temperature

air flows onto the windshield and the
front door windows (side air vents must
be open)

the air conditioning compressor
switches on at outside temperatures
above approximately 41°F (5°C) for
air-drying
If the automatic air distribution is switched
off:
Press air distribution button 9 or a
(
page 210).
Air recirculation mode
Switch to air recirculation mode to prevent
unpleasant odors from entering the vehicle
from the outside (e.g. before driving
through a tunnel). This setting cuts off the
intake of outside air and recirculates the
air in the passenger compartment.
iTo switch off, you can also press
button´ orU (
page 210).
iKeep this setting selected only until the
windshield is clear again.
Warning!G
Fogged windows impair visibility, endanger-
ing you and others. If the windows begin to
fog on the inside, switching off the air
recirculation mode immediately should clear
interior window fogging. If interior window
fogging persists, make sure the air
conditioning (
page 219) is activated, or
press button|.

217 Controls in detail
Climate control
Activating
Press button: (page 210).
The indicator lamp on the button
comes on.DeactivatingPress button:.
The indicator lamp on the button goes
out.Air recirculation mode with
convenience closing and opening
feature
iThe air recirculation mode is activated auto-
matically at high outside temperatures.
The indicator lamp on button: is not lit when
the air recirculation mode is switched on auto-
matically.
A quantity of outside air is added after approxi-
mately 30 minutes.
If you have turned off the air conditioning
(
page 219) or the outside temperature is
below 41°F (5°C), the air recirculation mode will
not switch on automatically.
iTo cool the interior as fast as possible, the
climate control automatically switches to air
recirculation. The indicator lamp on button:
is not lit when the air recirculation mode has
been switched on automatically.
iThe air recirculation mode is deactivated
automatically

after 5 minutes if the outside temperature is
below approximately 41°F (5°C)

after 5 minutes if the air conditioning and
air-drying are turned off

after 30 minutes if the outside temperature
is above approximately 41°F (5°C)
Warning!G
Never operate the windows and tilt/sliding
sunroof* or tilt/sliding panel* if there is the
possibility of anyone being harmed by the
opening or closing procedure.
In case the procedure causes potential dan-
ger:
Vehicles with or without tilt/sliding sun-
roof*: The closing of the windows can be im-
mediately halted by pressing or pulling the
respective window switch. The closing of the
tilt/sliding sunroof* can be immediately
halted by moving the switch for the
tilt/sliding sunroof* in any direction.
The closing of the windows and the
tilt/sliding sunroof* can be reversed by
again pressing and holding the: button.


218 Controls in detail
Climate control
Vehicles with tilt/sliding sunroof*
Convenience closing:
Press button: for approximately
2 seconds.
The windows and/or tilt/sliding sun-
roof will close. You can release
button: once the closing proce-
dure has begun. The windows and
tilt/sliding sunroof continue closing
until they are fully closed. The indicator
lamp on the button comes on. The air
recirculation mode is activated.Convenience opening:
Press button: for approximately
2 seconds.
The windows and/or tilt/sliding sun-
roof will return to their previous posi-
tions. You can release button:
once the opening procedure has
begun. The windows and tilt/sliding
sunroof continue opening until they
have reached their previous positions.
The indicator lamp on the button goes
out. The air recirculation mode is
deactivated.Vehicles with panorama roof*
Convenience closing:
Press and hold button: until the
windows and the tilt/sliding panel are
closed or have reached the desired
position. The indicator lamp on the
button comes on. The air recirculation
mode is activated.
Convenience opening:
Press and hold button: until the
windows and the tilt/sliding panel are
opened or have reached the desired
position. The indicator lamp on the
button goes out. The air recirculation
mode is deactivated.
Vehicles with panorama roof*: The closing
of the windows and tilt/sliding panel* can
be immediately halted by releasing
the:button.
iA window, the tilt/sliding sunroof*, or the
tilt/sliding panel* will only return to its previous
position if it has not been moved to another
position using the respective window switch or
tilt/sliding sunroof* (or tilt/sliding panel*)
switch after it was closed with button:.


219 Controls in detail
Climate control
Air conditioning
The air conditioning is operational while
the engine is running and cools the interior
air to the temperature set by the operator.
In addition, the air conditioning dehumidi-
fies the interior air at outside temperatures
above 41°F (5° C) and helps prevent
window fogging.
Deactivating
It is possible to deactivate the air condi-
tioning (cooling) function of the climate
control system. The air in the vehicle will
then no longer be cooled or dehumidified.Press button9 (page 210).
The indicator lamp on the button goes
out.
Activating
Moist air can fog up the windows. You can
dehumidify the air with the air condition-
ing.
Press button9 (page 210) again.
The indicator lamp on the button
comes on.
The air conditioning uses the refrigerant
R134a. This refrigerant is free of CFCs
which are harmful to the ozone layer.
Residual heat and ventilation
With the engine switched off, it is possible
to continue to heat or ventilate the interior
for up to 30 minutes. This feature makes
use of the residual heat produced by the
engine.
Activating
Switch off the ignition (page 39).
Press button9 (page 210).
The indicator lamp on the button
comes on.
iCondensation may drip out from underneath
the vehicle. This is normal and not an indication
of a malfunction.
Warning!G
If you turn off the cooling function, the inte-
rior air is not dried. The windows can fog up
more quickly. Window fogging may impair
visibility and endanger you and others.
!If the air conditioning cannot be turned on
again, this indicates that the air conditioning is
losing refrigerant. The compressor has turned
off.
Have the air conditioning checked at the nearest
authorized Mercedes-Benz Light Truck Center.
iHow long the system will provide heating
depends on

the coolant temperature

the battery voltage
Regardless of the temperature and air volume
set on the climate control panel, an interior tem-
perature is aimed at by 72°F (22°C) and the
blower runs on low speed to protect the vehicle
battery.