2008 MERCEDES-BENZ GL550 cooling

230 Controls in detail
3-zone automatic climate control*
1Temperature control, left
2Air distribution and air volume
(automatic, manual)
3Air distribution, driver’s side
4Front defroster
5Increasing air volume
6Rear window defroster
7Air distribution, passenger side
8Rear automatic climate control
on/off
>USA only
™Canada only
9Temperature control, right
aAutomatic climate control on/off
bAir distribution, passenger side
cAir distribution, passenger side
dAC cooling on/off
Residual heat/ventilation
eDisplay
fDecreasing air volume
gAir recirculation
hAir distribution, driver’s side
jAir distribution, driver’s side
kInterior temperature sensor
lAdopting driver’s side settings for all
zones
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232 Controls in detail
3-zone automatic climate control*
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 230).Deactivating the automatic climate
control system
Deactivating
Press button´ (page 230) until
the displaye (
page 230) is cleared.
The indicator lamp on the button
comes on.
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 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 249). The automatic 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.
Warning!G
When the automatic climate control system
is switched off, the outside air supply and
circulation are also switched off. Only
choose this settings for a short time. Other-
wise the windows could fog up, impairing
visibility and endangering you and others.
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233 Controls in detail
3-zone automatic climate control*
Reactivating
Press buttonU (page 230).Operating the automatic climate control system in automatic mode
You can switch the automatic climate con-
trol system on and off separately for each
zone as needed.
Activating
Press buttonU (page 230) while
the engine is running.
The indicator lamp on the button
comes on. Air volume and air distribu-
tion are controlled separately for each
zone.
Use temperature controls1 and9
(
page 230) to separately adjust the
air temperature on each side of the
passenger compartment.
The temperature of the interior is ad-
justed automatically.
Deactivating
Press one button of the air distribution
(
page 230) or press button

orQ (
page 230).
The indicator lamp on buttonU
goes out.
Depending on which button you press –
the air distribution button or the air vol-
ume button
orQ – automatic
control of either the air distribution or
air volume is switched off.
iYou can also press button´
(
page 230) on the automatic climate control
panel.
If you press button| (
page 230) to
reactivate the automatic climate control system,
the defrosting mode is activated.iWhen operating the automatic climate
control system in automatic mode, you will only
rarely need to adjust the temperature, air volume
and air distribution.
In automatic mode, cooling with dehumidify is
switched on. This function can be switched off if
necessary.
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237 Controls in detail
3-zone automatic climate control*
Windshield fogged on the outside
Switch the windshield wipers on
(
page 63).
Press buttonU (page 230).
The indicator lamp on buttonU
goes out. Air volume and air
distribution are controlled separately
for each zone.
If the automatic air distribution and
air volume are switched off:
Press buttons8 andY
(
page 230).
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 front and rear
display.
This provides the fastest possible cooling
of the vehicle interior (when windows and
tilt/sliding sunroof* 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.
iKeep this setting selected only until the
windshield is clear again.
Warning!G
Fogged windows impair visibility,
endangering 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 win-
dow fogging persists, make sure the air
conditioning (
page 239) is activated, or
press button|.
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239 Controls in detail
3-zone automatic climate control*
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 be-
gun. The windows and tilt/sliding sun-
roof* continue opening until they have
reached their previous positions. The
indicator lamp on the button goes out.
The air recirculation mode is deactivat-
ed.
Air conditioning
The cooling function, only operational
when the engine is running, cools the vehi-
cle down to the selected interior tempera-
ture. The cooling function also
dehumidifies the air in the vehicle interior,
thereby preventing the windows from fog-
ging up.The closing of the side windows and the
tilt/sliding sunroof* can be reversed by
again pressing and holding the :button.
iA window or the tilt/sliding sunroof* will
only return to its previous position if it has not
been moved to another position using the re-
spective window switch or tilt/sliding sunroof*
switch after it was closed with button:.
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.
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240 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 vehi-
cle will then no longer be cooled or dehu-
midified.
Press button9 (page 230).
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 tem-
perature 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 230).
Press button; (page 230).
The indicator lamp on the button
comes on.
The driver-side settings are used for all
temperature zones.
Deactivating
Press button; (page 230) again.
The indicator lamp on the button goes
out.
!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.
iIf you manually set the temperature, air vol-
ume or air distribution for the passenger side or
the rear passenger compartment when the
MONO setting is active, the MONO setting will
be switched off.
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242 Controls in detail
3-zone automatic climate control*
Activating rear automatic climate
control
Press buttonU.
The indicator lamp on the button
comes on. The temperature, air vol-
ume, and air distribution are adjusted
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.Operating from the front
Deactivating
Press button> (page 230).
The indicator lamp on the button goes
out.
In displaye (
page 230), you will see
the> symbol followed by
MODE for
approximately 3 seconds.
Press button´ (page 230).
In displaye (
page 230), you will see
the> symbol followed by
OFF.
The rear automatic climate control is
switched off.
1Left rear center air vent, adjustable
2Right rear center air vent, adjustable
3Temperature control
4Air distribution and air volume
(automatic, manual)
5Air distribution (directs air through
the center air vents)
6Air distribution (directs air through
the footwells and side air vents)
7Rear automatic climate control
on/off
8Decreasing air volume
9Indicator lamps for air volume
settings
aIncreasing air volume
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 233).
iSwitch off the rear automatic climate con-
trol 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 com-
partment (
page 230).
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382 Operation
Engine compartment
The coolant expansion tank is located on
the driver’s side of the engine compart-
ment.
1Cap
2Coolant expansion tank
3Indicator wall
4Coolant levelUsing a rag, turn cap1 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap1 counterclock-
wise and remove it.
Coolant level4 is correct if the level:

for cold coolant: reaches the top of
indicator wall3 visible through the
filling opening

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
“Coolants” (
page 567).
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 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 1/2 turn to relieve excess pres-
sure. If opened immediately, scalding
hot fluid and steam will be blown out
under pressure.

Do not spill antifreeze on hot engine
parts. Antifreeze contains ethylene
glycol which may burn if it comes into
contact with hot engine parts.
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