cooling MERCEDES-BENZ R320 2008 W251 User Guide

231 Controls in detail
3-zone automatic climate control*
Maximum cooling MAXCOOL
If the air distribution control as well as the
airflow volume control are set toU and
there is a high need for cooling, the
MAXCOOL function is activated.
“
MAXCOOL” appears in the display.
This provides the fastest possible cooling
of the vehicle interior (when windows and
tilt/sliding sunroof* or tilt/sliding panel*
are closed).
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 224).
The indicator lamp on the button
comes on.
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 233) is activated, or
press button|.
iThe air recirculation mode is activated
automatically at high outside temperatures.
The indicator lamp on button:is not lit
when the air recirculation mode is switched on
automatically.
A quantity of outside air is added after
approximately 30 minutes.
If you have turned off the air conditioning
(
page 233) 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 automatic climate control automatically
switches to air recirculation. The indicator lamp
on button: is not lit when the system
switches to air recirculation automatically.

233 Controls in detail
3-zone automatic climate control*
Convenience opening:
Press button: for approximately
2 seconds.
The windows and/or tilt/sliding
sunroof will return to their previous
positions. 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 po-
sition. 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.
Air conditioning
The cooling function, only operational
when the engine is running, cools the
vehicle down to the selected interior
temperature. The cooling function also
dehumidifies the air in the vehicle interior,
thereby preventing the windows from
fogging up.
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
interior air is not dried. The windows can fog
up more quickly. Window fogging may
impair visibility and endanger you and
others.

234 Controls in detail
3-zone automatic climate control*
Deactivating
It is possible to deactivate the air condi-
tioning (cooling) function of the automatic
climate control system. The air in the
vehicle will then no longer be cooled or
dehumidified.
Press button9 (page 224).
The indicator lamp on the button goes
out. The cooling function switches off
after a short delay.Activating
Moist air can fog up the windows. You can
dehumidify the air with the air condition-
ing.
Press button9 again.
The indicator lamp on the button
comes on.
The air conditioning uses the refrigerant
R-134a. This refrigerant is free of CFCs
which are harmful to the ozone layer.Using driver-side settings for all
temperature zones
You can use the settings of the driver’s
side, such as temperature, air volume and
air distribution, for all temperature zones.
These settings only need to be made once
and the automatic climate control system
will automatically regulate the settings for
all temperature zones quickly and comfort-
ably.
Activating
Adjust the temperature, air volume and
air distribution (
page 224).
Press button; (page 224).
The indicator lamp on the button
comes on.
The driver-side settings are used for all
temperature zones.
!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.

236 Controls in detail
3-zone automatic climate control*
Rear automatic climate control
(second row)
The control panel is located at the rear of
the front center console.
Rear automatic climate control panel
Activating rear automatic climate
control
Press buttonU.
The indicator lamp on the button
comes on. The temperature, air
volume, and air distribution are ad-
justed automatically.
Deactivating rear automatic climate
control
Press button´.
The indicator lamp on the button goes
out.
The cooling function switches off after
a short delay.
1Increasing air volume
2Air distribution and air volume
(automatic, manual)
3Air distribution (directs air through
the side air vents)
4Right rear center air vent, adjustable
5Air distribution (directs air through
the footwells and side air vents)
6Rear automatic climate control
on/off
7Decreasing air volume
8Left rear center air vent, adjustable
9Indicator lamps for air volume
settings
aTemperature control
iThe stored values for the rear automatic
climate control are erased from memory after
the ignition has been switched off for more than
30 minutes. Once the front automatic climate
control is switched on again, the rear automatic
climate control operates in automatic mode at a
preset temperature of 72°F (22°C).
iThe automatic climate control must be
switched on (
page 226).
iSwitch off the rear automatic climate
control for improved cooling or heating output in
the front passenger compartment.
You can also switch off the rear automatic
climate control from the front passenger
compartment (
page 237).

360 Operation
Engine compartment
Be careful not to spill any oil when adding.
Avoid environmental damage caused by oil
entering the ground or water.
Screw filler cap1 back on filler neck.
For more information on engine oil, see
“Technical data” section (
page 536) and
(
page 538).
Transmission fluid level
The transmission fluid level does not need
to be checked. If you notice transmission
fluid loss or gear shifting malfunctions,
have an authorized Mercedes-Benz Light
Truck Center check the automatic trans-
mission.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.
!Excess oil must be siphoned or drained off.
It could cause damage to the engine or
emission control system not covered by the
Mercedes-Benz Limited Warranty.
Warning!G
In order to avoid any 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 display
indicates 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 1/2turn to relieve excess pres-
sure. If opened immediately, scalding


448 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
•Coolant Level
Stop car, switch engine off.The coolant is too hot.
Among other possible causes
(the cooling fan could be
malfunctioning), the poly-V-belt
could be broken.Stop the vehicle in a safe location or
as soon as it is safe to do so.
Turn off the engine.
Apply the parking brake (page 65).
Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine.
Contact an authorized
Mercedes-Benz Light Truck Center.
If it is intact:
Wait for the message to disappear
before restarting the engine.
Doing otherwise could result in seri-
ous engine damage that is not
covered by the Mercedes-Benz
Limited Warranty.
(Continued on next page)

450 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
B Top Up Coolant
See Operator’s ManualThe coolant level is too low.Add coolant (page 360).
If you have to add coolant frequently,
have the cooling system checked by an
authorized Mercedes-Benz Light Truck
Center.
Warning!G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You could be seriously burned.
!Do not ignore the low engine coolant level
warning. Extended driving with the message and
symbol displayed may cause serious engine
damage not covered by the Mercedes-Benz
Limited Warranty.
Do not drive without sufficient amount of coolant
in the cooling system. The engine will overheat,
causing major engine damage.

466 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
n*Compressor
Cooling DownLevel control was activated too long/too
frequently.Let the compressor cool until the
message disappears.
The selected level will be set once the
compressor has cooled down.
MalfunctionThe AIRMATIC* is malfunctioning.Do not drive faster than
50 mph (80 km/h) depending on
the set vehicle level.
Have the system checked at an
authorized Mercedes-Benz Light
Truck Center.
!When the message Compressor Cooling
Down
appears in the multifunction display, driv-
ing is still possible. Keep in mind that the ride
height of the vehicle is not yet reached and you
could therefore damage the underbody of the
vehicle. The selected level will be set once the
compressor has cooled down.

537 Technical data
Fuels, coolants, lubricants, etc.
ModelCapacityFuels, coolants, lubricants, etc.
Power steeringapprox. 1.3 US qt (1.2 l)MB Power Steering Fluid or approved
Dexron III ATF
Front wheel hubsapprox. 1.5 oz (43 g) eachHigh temperature roller bearing grease
Brake systemMB Brake Fluid (DOT 4+)
Cooling systemR 320 CDI 4MATIC10.0 US qt (9.5 l)MB Anticorrosion/Antifreeze
R 3501, R 350 4MATIC
1USA only.
10.0 US qt (9.5 l)
R 550 4MATIC2
2Canada only.
12.7 US qt (12 l)
Fuel tank
including a reserve of21.1 US gal (80.0 l)
approx. 3.4 US gal (13.0 l)Gasoline engine:
Premium unleaded gasoline:
Minimum Posted Octane 91
(Avg.of96RON/86MON)
Diesel engine:
ULTRA-LOW SULFUR HIGHWAY DIESEL
FUEL (15 ppm SULFUR MAXIMUM)

541 Technical data
Fuels, coolants, lubricants, etc.
In areas where carbon deposits may be
encountered due to lack of availability of
gasolines which contain these additives,
Mercedes-Benz recommends the use of
additives approved by us for use on
Mercedes-Benz vehicles. Refer to Factory
Approved Service Products pamphlet (USA
only) or contact an authorized
Mercedes-Benz Light Truck Center for a
listing of approved product(s). Follow
directions on product label.
Do not blend other specific fuel additives
with fuel. This only results in unnecessary
costs and may be harmful to the engine
operation.Coolants
The engine coolant is a mixture of water
and anticorrosion/antifreeze, which
provides:

Corrosion protection

Freeze protection

Boiling protection (by increasing the
boiling point)
The cooling system was filled at the factory
with a coolant providing freeze protection
to approximately -35°F (-37°C) and
corrosion protection.If the antifreeze mixture is effective to
-35°F (-37°C), the boiling point of the cool-
ant in the pressurized cooling system is
reached at approximately 266°F (130°C).
The coolant solution must be used year
round to provide the necessary corrosion
protection and increase boil-over protec-
tion. Refer to Maintenance Booklet for
replacement interval.
!Damage or malfunction resulting from poor
fuel quality or from blending additional fuel
additives other than those tested and approved
by us for use on Mercedes-Benz vehicles are not
covered by the Mercedes-Benz Limited
Warranty.
! Add premixed coolant solution only. Adding
water and MB 325.0 Anticorrosion/Antifreeze
separately from each other, could cause engine
damage not covered by the Mercedes-Benz
Limited Warranty.