2008 MERCEDES-BENZ C300 cooling

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.

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.

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.

268 Controls in detail
3-zone automatic climate control* (Canada only)
Rear climate control
The rear climate control panel is located in
the rear center console.
Setting temperature
Use temperature control 5 to adjust the
air temperature in the rear passenger com-
partment. You should raise or lower the
temperature setting in small increments,
preferably starting at 22°C (72°F). The cli-
mate control will adjust to the set temper-
ature as fast as possible.Increasing/decreasing: Press the re-
spective temperature control
button5.
The 3-zone automatic climate control
system will correspondingly adjust the
temperature in the rear passenger
compartment.
Adjusting air volume
Use button· orQ (
page 268) to
adjust the air volume.
Press button· to decrease, or
buttonQ to increase air volume to
the desired level.
The air volume is adjusted correspond-
ing to the set blower speed.
Warning!G
Follow the recommended settings for heat-
ing and cooling as given in the instructions
for the front 3-zone automatic climate con-
trol (
page 259). Otherwise the windows
could fog up, impairing visibility for the driv-
er and endangering you and others.
Item
1Decreasing/increasing air volume
for rear center air vents
2Right rear center air vent, adjustable
3Decreasing/increasing air volume
for rear center air vents
4Display
5Temperature control
6Left rear center air vent, adjustable
iAt low outside temperatures or if you have
switched off the cooling function, you cannot
cool the rear passenger compartment.
iIf you have switched off the cooling function
with the front 3-zone automatic climate control
panel, the cooling of the rear passenger com-
partment is also switched off. Adjusting with the
rear control panel is not possible.

329 Operation
Engine compartment
Coolant level
The engine coolant is a mixture of water
and anticorrosion/antifreeze. To check
the coolant level, the vehicle must be
parked on level ground and the engine
must be cool.
The coolant expansion tank is located on
the passenger side of the engine compart-
ment.
1Cap
2Coolant expansion tank
3Fluid level bridgeUsing a rag, turn cap1 slowly approx-
imately a half-turn counterclockwise to
release any excess pressure.
Continue turning the cap1 counter-
clockwise and remove it.
The coolant level is correct if the level

for cold coolant: reaches the white
marking (plastic bridge)3 inside the
coolant expansion tank2

for warm coolant: is approximately
0.6 in (1.5 cm) higher
Add coolant as required.
Replace and tighten cap1.
For more information on coolant, see the
“Technical data” section (
page 484).
Warning!G
In order to avoid potentially serious burns:

Use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking from the cooling system,
or if the coolant temperature gauge indi-
cates that the coolant is overheated.

Do not remove pressure cap on coolant
reservoir if coolant temperature is
above 158°F (70°C). Allow engine to
cool down before removing cap. The
coolant reservoir contains hot fluid and
is under pressure.

Using a rag, slowly open the cap approx-
imately a half-turn to relieve excess
pressure. If opened immediately, scald-
ing hot fluid and steam will be blown out
under pressure.

Do not spill antifreeze on hot engine
parts. Antifreeze contains ethylene gly-
col which may burn if it comes into con-
tact with hot engine parts.