2008 MERCEDES-BENZ C300 engine

252 Controls in detail
Dual-zone automatic climate control
Deactivating the climate control
system
Deactivating: Press button´
(
page 250).
The indicator lamp in the button comes
on.
Reactivating: Make sure the ignition is
switched on.
Press button´ (page 250) again.
The indicator lamp in the button goes
out.The previous settings are once
again in effect.
or,
Press buttonU (page 250) while
the engine is running.
The indicator lamp in the button comes
on. The air volume and air distribution
are adjusted automatically.
iKeep the air intake grille in front of the wind-
shield free of snow and debris.
Do not obstruct air flow by placing objects on the
air flow-through exhaust slots below the rear
window.
iIf the vehicle interior is hot, ventilate the in-
terior before driving off, see “Summer opening
feature” (
page 123). The climate control will
then adjust the interior temperature to the set
value much faster.
Warning!G
When the climate control is switched off, the
outside air supply and circulation 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.

253 Controls in detail
Dual-zone automatic climate control
Operating the climate control system
in automatic mode
Activating: Press buttonU
(
page 250) while the engine is run-
ning.
The indicator lamp in the button comes
on. The air volume and air distribution
are adjusted automatically.
Use temperature controls1 and6
(
page 250) to separately adjust the
air temperature on each side of the
passenger compartment.
The temperature of the vehicle interior
is adjusted automatically.
Deactivating: Press buttonU
(
page 250) again.
The indicator lamp in the button goes
out. The automatic operation of air vol-
ume and air distribution switches off.
The symbols of air distribution and air
volume appear in displayb.
Adjust air distribution (page 254).
Adjust air volume (page 254).
Setting the temperature
Use temperature controls1 and6
(
page 250) 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
control1 and/or6 (
page 250)
slightly clockwise.
The climate control system will corre-
spondingly adjust the interior air tem-
perature.
Decreasing: Turn temperature
control1 and/or6 (
page 250)
slightly counterclockwise.
The climate control system will corre-
spondingly adjust the interior air tem-
perature.
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 258).

258 Controls in detail
Dual-zone automatic climate control
Air conditioning
The cooling function, only operational
when the engine is running, cools the vehi-
cle interior down to the selected tempera-
ture. The cooling function also
dehumidifies the air in the vehicle interior,
thus preventing the windows from fogging
up.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.
Deactivating: Press button2
(
page 250).
The indicator lamp in the button goes
out.
The cooling function switches off after
a short delay.
Moist air can fog up the windows. You can
dehumidify the air with the air condition-
ing.
Activating: Press button2
(
page 250) again.
The indicator lamp in the button comes
on.
The air conditioning uses the
refrigerant R134a. This refrigerant is free
of CFCs which are harmful to the ozone
layer.
Warning!G
If you turn off the cooling function, the
vehicle will not be cooled when weather
conditions are warm and the interior air is
not dried. The windows can fog up more
quickly. Window fogging may impair visibili-
ty and endanger you and others.
iCondensation may drip out from underneath
the vehicle. This is normal and not an indication
of a malfunction.
!If the air conditioning cannot be turned on
again, this indicates that the air conditioning is
losing refrigerant. The compressor has turned it-
self off.
Have the air conditioning checked at the nearest
authorized Mercedes-Benz Center.

259 Controls in detail
3-zone automatic climate control* (Canada only)
3-zone automatic climate control* (Canada only)
3-zone automatic climate control panel, front
Item
1Temperature control, driver’s side
2UAir distribution and air vol-
ume (automatic mode)
3´Automatic climate control
on/off
4zAdopting driver’s side set-
tings for all zones
Item
52AC cooling on/off
6TResidual engine
heat/ventilation
7yFront defroster
8Temperature control, passenger side
9¯Rear window defroster
Item
aZAir distribution, passenger
side
bQIncreasing air volume
c·Decreasing air volume
dDisplay
eZAir distribution, driver’s side
f,Air recirculation

260 Controls in detail
3-zone automatic climate control* (Canada only)
The 3-zone automatic climate control is
operational whenever the engine is run-
ning. You can operate the 3-zone automat-
ic 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.
It can only function optimally when you are
driving with the windows and the tilt/slid-
ing sunroof/panorama sunroof* closed.It is possible to completely deactivate the
3-zone automatic climate control system
(
page 261).
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 267).
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 on unpro-
tected skin in the immediate area of the air
vents. Always keep sufficient distance be-
tween unprotected parts of the body and the
air vents. If necessary, use the air
distribution control (page 248) to direct
the air to air vents in the vehicle interior that
are not in the immediate area of unprotect-
ed skin.
Warning!G
Severe conditions (e.g. strong air pollution)
may require replacement of the filter before
its scheduled 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 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.
iKeep the air intake grille in front of the wind-
shield free of snow and debris.
Do not obstruct air flow by placing objects on the
air flow-through exhaust slots below the rear
window.
iIf the vehicle interior is hot, ventilate the in-
terior before driving off, see “Summer opening
feature” (
page 123). The climate control will
then adjust the interior temperature to the set
value much faster.

261 Controls in detail
3-zone automatic climate control* (Canada only)
Deactivating climate control system
Deactivating: Press button´
(
page 259).
The indicator lamp in the button comes
on.
Reactivating: Make sure the ignition is
switched on.
Press button´ (page 259) again.
The indicator lamp in the button goes
out.The previous settings are once
again in effect.
or,
Press buttonU (page 259) while
the engine is running.
The indicator lamp in the button comes
on. The air volume and air distribution
are adjusted automatically.Operating climate control system in
automatic mode
Activating: Press buttonU
(
page 259) while the engine is run-
ning.
The indicator lamp in the button comes
on. The air volume and air distribution
are adjusted automatically.
Use temperature controls1 and8
(
page 259) to separately adjust the
air temperature on each side of the
passenger compartment.
The temperature of the vehicle interior
is adjusted automatically.
Warning!G
When the climate control is switched off, the
outside air supply and circulation 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.
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.

266 Controls in detail
3-zone automatic climate control* (Canada only)
Activating: Press button,
(
page 259).
The indicator lamp in the button comes
on.
Deactivating: Press button,
(
page 259) again.
The indicator lamp in the button goes
out.
Residual engine heat and ventilation
With the engine switched off, it is possible
to continue to heat or ventilate the interior
for approximately 30 minutes. This feature
makes use of the residual heat produced
by the engine.
Activating: Switch off the ignition.
Press buttonT (page 259).
The indicator lamp in the button comes
on.
Deactivating: Press buttonT
(
page 259) again.
The indicator lamp in the button goes
out.
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 automatically
switched on.
A quantity of outside air is added after approxi-
mately 30 minutes.
iThe air recirculation mode is deactivated au-
tomatically:

after 5 minutes if the outside temperature is
below approximately 7°C (45°F)

after 5 minutes if the air conditioning is
turned off

after 30 minutes if the outside temperature
is above approximately 5°C (41°F)
iIf you switch on the residual heat function
when outside temperatures are high, only the
ventilation will be switched on.
iRegardless of the selected air volume, the
blower operates at low speed when heating. In
case of ventilation the blower operates at higher
speed.
iHow long the system will provide heating de-
pends on

the coolant temperature

the temperature set by the operator
iThe residual heat is automatically turned off:

when the ignition is switched on

after approximately 30 minutes

if the battery voltage drops

if the coolant temperature is too low

267 Controls in detail
3-zone automatic climate control* (Canada only)
Air conditioning
The cooling function, is only operational
when the engine is running, cools the vehi-
cle interior down to the selected tempera-
ture. The cooling function also
dehumidifies the air in the vehicle interior,
thus preventing the windows from fogging
up.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.
Deactivating: Press button2
(
page 250).
The indicator lamp in the button goes
out.
The cooling function switches off after
a short delay.
Moist air can fog up the windows. You can
dehumidify the air with the air condition-
ing.
Activating: Press button2
(
page 250) again.
The indicator lamp in the button comes
on.
The air conditioning uses the
refrigerant R134a. This refrigerant is free
of CFCs which are harmful to the ozone
layer.
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
vehicle will not be cooled when weather
conditions are warm. 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 it-
self off.
Have the air conditioning checked at the nearest
authorized Mercedes-Benz Center.