2008 MERCEDES-BENZ C300 air condition

255 Controls in detail
Dual-zone automatic climate control
Front defroster
You can use this setting to defrost the
windshield, for example if it is iced up.
You can also defog the windshield and the
side windows.
Activating: Press buttony
(
page 250).
The indicator lamp in the button comes
on.
The air conditioning switches
automatically to the following func-
tions:

cooling on to dehumidify

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

air flows onto the windshield
and the front side windows

the air recirculation mode is
switched off
Deactivating: Press buttony
(
page 250) again.
The indicator lamp in the button goes
out. Defrosting is turned off.
The previous settings are once again in
effect.Windshield fogged on the outsideSwitch the windshield wipers on
(
page 117).
If the automatic mode of the climate con-
trol is switched off:
Press buttonZ (page 250) re-
peatedly until one of the following sym-
bols appears in displayb:a
orY (
page 250).
iKeep this setting selected only until the
windshield or the side windows are clear again.
iYou can adjust the temperature and the air
volume when the front defroster is switched on.
iTo switch defrosting off, you can also press
button´, U,·,Q or temperature
controls1 and6 (
page 250).
iThe cooling remains switched on.
iKeep this setting selected only until the
windshield is clear again.

256 Controls in detail
Dual-zone automatic climate control
Maximum cooling MAX COOL
(USA only)
You can use this setting to provide the fast-
est possible cooling of the vehicle interior
(when windows and tilt/sliding sunroof or
tilt/sliding panel* are closed).
Activating: Press button3
(
page 250).
The indicator lamp in the button comes
on.
The air conditioning switches
automatically to the following functions:

maximum cooling

maximum blowing power

the air recirculation mode is switched
on
Deactivating: Press button3
(
page 250) again.
The indicator lamp in the button goes
out. The previous settings are once
again in effect.
Rear window defroster
Activating: Switch on the ignition.
Press button¯ (page 250).
The indicator lamp in the button comes
on.
iTo switch the maximum cooling function off,
you can also press button ´, U ory
(
page 250).
Warning!G
Any accumulation of snow and ice should be
removed from the rear window before driv-
ing. Visibility could otherwise be impaired,
endangering you and others.
!The rear window defroster uses a large
amount of power. To keep battery drain to a min-
imum, switch off the defroster as soon as the
rear window is clear.

257 Controls in detail
Dual-zone automatic climate control
Deactivating: Press button¯
(
page 250).
The indicator lamp in the button goes
out.
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.Activating: Press button,
(
page 250).
The indicator lamp in the button comes
on.
Deactivating: Press button,
(
page 250) again.
The indicator lamp in the button goes
out.
iThe rear window defroster is automatically
deactivated after some time of operation de-
pending on the outside temperature.
iIf the rear window defroster switches off too
soon and the indicator lamp goes out, this indi-
cates that too many electrical consumers are op-
erating simultaneously and the load on the
battery is reducing available voltage. The system
responds automatically by deactivating the rear
window defroster.
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 258) is activated, or
press buttony.
iThe air recirculation mode is activated auto-
matically at high outside temperatures.
The indicator lamp in 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 41°F (5°C)

after 5 minutes if the air conditioning is
turned off

after 30 minutes if the outside temperature
is above approximately 41°F (5°C)

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.

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.

264 Controls in detail
3-zone automatic climate control* (Canada only)
Front defroster
You can use this setting to defrost the
windshield, for example if it is iced up. You
can also defog the windshield and the side
windows.
Activating: Press buttony
(
page 259).
The indicator lamp in the button comes
on.
The air conditioning switches
automatically to the following functions:

cooling on to dehumidify

most efficient blower speed and
heating power, depending on out-
side temperature

air flows onto the windshield and
the front side windows

the air recirculation mode is
switched off
Deactivating: Press buttony
(
page 259) again.
The indicator lamp in the button goes
out. Defrosting is turned off.
The previous settings are once again in
effect.Windshield fogged on the outsideSwitch the windshield wipers on
(
page 118).
If the automatic mode of the climate con-
trol is switched off:
Press righta and/or lefte air distri-
bution buttonZ (
page 259) re-
peatedly until one of the following
symbols appears in
displayd:aorY
(
page 259).
iKeep this setting selected only until the
windshield is clear again.
iYou can adjust the air distribution when the
front defroster is switched on.
iTo switch defrosting off, you can also press
button´, U,·,Q or temperature
controls1 and8 (
page 259).
iThe cooling remains switched on.
iKeep this setting selected only until the
windshield is clear again.

265 Controls in detail
3-zone automatic climate control* (Canada only)
Rear window defroster
Activating: Switch on the ignition.
Press button¯ (page 259).
The indicator lamp in the button comes
on.
Deactivating: Press button¯
(
page 259).
The indicator lamp in the button goes
out.
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.
!The rear window defroster uses a large
amount of power. To keep battery drain to a min-
imum, switch off the defroster as soon as the
rear window is clear.
iThe rear window defroster is automatically
deactivated after some time of operation de-
pending on the outside temperature.
Warning!G
Any accumulation of snow and ice should be
removed from the rear window before driv-
ing. Visibility could otherwise be impaired,
endangering you and others.
iIf the rear window defroster switches off too
soon and the indicator lamp goes out, this indi-
cates that too many electrical consumers are op-
erating simultaneously and the load on the
battery is reducing available voltage. The system
responds automatically by deactivating the rear
window defroster.
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 267) is activated, or
press buttony.

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