2012 MERCEDES-BENZ B-CLASS cooling

for the front-passenger side as well. The
indicator lamp
in
the á button goes out.
R Use the residual heat function if you want
to heat or ventilate the vehicle interior
when the ignition is switched off. The
residual heat function can only be activated
or deactivated with the ignition switched
off.
ECO start/stop function During automatic engine switch-off, the ECO
start/stop function only operates at a
reduced capacity. If you require the full
climate control
output,

you can switch off the
ECO start/stop function by pressing the ECO
button ( Y page 138). Operating the climate control
systems
Switching climate control on/off
Points to observe before use When the climate control is switched off, the
air supply and air circulation are also
switched off. The windows could fog up.
Therefore, switch off climate control only
briefly
Activating/deactivating
Automatic climate control
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To switch on: turn control A
clockwise to
the desired position (except position 0)
(Y page 119).
X To switch off: turn control A counter-
clockwise to position 0(Y page 119). Dual-zone automatic climate control
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To activate: press the à button.
The indicator
lamp

in the à button lights
up. Airflow and air distribution are set to
automatic mode.
or
X Press the ^ button.
The indicator lamp

in the ^ button goes
out. The previously selected settings are
restored.
X To deactivate: press the ^ button.
The indicator lamp

in the ^ button lights
up.
i Dual-zone automatic climate control:
switch on climate control primarily using
the à button. Activating/deactivating cooling with
air dehumidification
Points to observe before use If you deactivate the "Cooling with air-
dehumidification" function, the air inside the
vehicle will not be cooled. The air inside the
vehicle will also not be dehumidified. The
windows can
fog

up more quickly. Therefore,
only deactivate the "Cooling with air-
dehumidification" function briefly.
The cooling with air dehumidification function
is only available when the engine is running.
The air inside the vehicle is cooled and
dehumidified according to the temperature
selected.
Condensation may drip from the underside of
the vehicle when it is in cooling mode. This is
normal and not a sign that there is a
malfunction. Operating the climate control systems
123
Climate control
ProCarManuals.com

Activating/deactivating
X
To activate: press the ¿ button.
The indicator lamp
in the ¿ button lights
up.
X To deactivate: press the ¿ button.
The indicator lamp

in the ¿ button goes
out. The "Cooling with air dehumidification"
function has a delayed switch-off feature. 124
Operating the climate control systems
Climate control
ProCarManuals.com

Problems with the "Cooling with air dehumidification" function
Problem Possible causes/consequences and
M SolutionsThe indicator lamp in
the ¿ button
flashes three times or
remains off. The
"Cooling with air
dehumidification"
function cannot be
switched on. Cooling with air dehumidification has been deactivated due to a
malfunction.
X
Visit a qualified specialist workshop. Setting the climate control to
automatic
The automatic function is only available in
conjunction with dual-zone
automatic climate
control.
In automatic mode, the set temperature is
maintained automatically at a constant level.
The system automatically regulates the
temperature of the dispensed air, the airflow
and the air distribution.
The automatic mode functions optimally
when the "Cooling with air dehumidification"
function is activated. If necessary, cooling
with air dehumidification can be deactivated.
If you deactivate the "Cooling with air-
dehumidification" function, the air inside the
vehicle will not be cooled. The air inside the
vehicle will also not be dehumidified. The
windows can fog up more quickly. Therefore,
only deactivate the "Cooling with air-
dehumidification" function briefly.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Set the desired temperature.
X To activate: press the à button.
The indicator lamp

in the à button lights
up. Automatic air distribution and airflow
are activated. X
To switch to manual mode: press the
É or Ë button.
or
X Press the K or I button.
The indicator lamp

in the à button goes
out. Automatic air distribution and airflow
are deactivated. Setting the temperature
Automatic climate control You can set the temperature for the entire
vehicle.
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To increase/reduce: turn control :
clockwise or counter-clockwise
(Y page 119).

Only change the temperature
setting in small increments. Start at 72 ‡
(22 †).
Dual-zone automatic climate control Different temperatures can be set for the
driver's and front-passenger sides.
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To increase/reduce: turn control : or
E clockwise or counter-clockwise
(Y page
121).

Only change the temperature Operating the climate control systems
125
Climate control
ProCarManuals.com

Defrosting the windshield
You can use this function to defrost the
windshield or to defrost the inside of the
windshield and the side windows.
i You should only select the "windshield
defrosting" function until the windshield is
clear again.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To activate: press the ¬ button.
The indicator lamp
in the ¬ button lights
up.
The climate control system switches to the
following functions:
R high airflow
R high temperature
R air distribution to the windshield and
front side windows
R air-recirculation mode off
i The "windshield defrosting" function
automatically sets the

blower output to the
optimum defrosting effect. As a result, the
airflow may increase or decrease
automatically after the button is pressed.
i You can adjust the blower output
manually while the "Windshield defrosting"
function is in operation:
R Automatic climate control: turn airflow
control A clockwise or counter-
clockwise (Y page 119).
R Dual-zone automatic climate control:
press the ó or ô button.
X To deactivate: press the ¬ button.
The indicator lamp

in the ¬ button goes
out. The previously selected settings are
restored. Air-recirculation mode remains
deactivated.
or X
Press the à button. 5
The indicator
lamp

in the ¬ button goes
out. Airflow and air distribution are set to
automatic mode.
or
X Automatic climate control: turn
temperature control : clockwise or
counter-clockwise ( Y page 119).
Dual-zone automatic climate control:
turn temperature controls : or E
clockwise or counter-clockwise
(Y page 121). MAX COOL maximum cooling
The MAX COOL function is only available in
vehicles for the USA.
MAX COOL is only operational when the
engine is running.
X To activate: press the Ù button.
The indicator lamp in the button lights up.
X To deactivate: press the Ù button
again.
The indicator lamp

goes out. The previously
selected settings are restored.
When you activate MAX COOL, climate
control switches to the following functions:
R maximum cooling
R maximum airflow
R air-recirculation mode on Defrosting the windows
Windows fogged up on the inside Automatic climate control
X
Activate the ¿ "Cooling with air
dehumidification" function.
X If the windows continue to fog up, activate
the "windshield defrosting" function
(Y page 127).
5 3-zone automatic climate control only. Operating the climate control systems
127Climate control
ProCarManuals.com

i
You should only select this setting until
the windshield is clear again.
Dual-zone automatic climate control
X Activate the ¿ "Cooling with air
dehumidification" function.
X Activate automatic mode Ã.
X If the windows continue to fog up, activate
the "windshield defrosting" function
(Y page 127).
i You should only select this setting until
the windshield is clear again.
Windows fogged up on the outside X
Activate the windshield wipers.
X Set the air distribution to P or O.
i You should only select this setting until
the windshield is clear again. Rear window defroster
Activating/deactivating The rear window defroster has a high current
draw. You should therefore switch it off as
soon as the rear window is clear. Otherwise,
the rear window defroster switches off
automatically after several minutes.
If the battery voltage is too low, the rear
window defroster may switch off.
X
Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Press the ¤ button.
The indicator lamp
in the ¤ button lights
up or goes out. 128
Operating the climate control systems
Climate control
ProCarManuals.com

Problems with the rear window defroster
Problem Possible causes/consequences and
M SolutionsThe rear window
defroster has
deactivated
prematurely or cannot
be activated. The battery has not been sufficiently charged.
X
Switch off any consumers that are not required, e.g. reading
lamps, interior lighting or the seat heating.
When the battery is sufficiently charged, the rear window
defroster can be activated again. Activating/deactivating air-
recirculation mode
If you switch on air-recirculation mode, the
windows can fog up more quickly, in
particular at low temperatures. Only use air-
recirculation mode briefly to prevent the
windows from fogging up.
You can deactivate the flow of fresh air if
unpleasant odors are entering the vehicle
from outside. The air already inside the
vehicle will then be recirculated.
The operation of
air-recirculation mode is the
same for all control panels.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X To activate: press the e button.
The indicator lamp

in the e button lights
up.
i Air-recirculation mode is activated
automatically at high outside
temperatures. When air-recirculation

mode
is activated automatically, the indicator
lamp in the e button is not lit.
Outside air is added after about
30 minutes.
X To deactivate: press the e button.
The indicator lamp

in the e button goes
out. i
Air-recirculation mode deactivates
automatically:
R after approximately five minutes at
outside temperatures below
approximately 41 ‡ (5 †)
R after approximately five minutes if the
"Cooling with air dehumidification"
function is deactivated
R after approximately 30 minutes at
outside temperatures above
approximately

41 ‡(5 †) if the "Cooling
with air dehumidification" function is
activated Activating/deactivating the residual
heat function
The residual heat

function is only available in
vehicles for Canada with dual-zone automatic
climate control.
It is possible to make use of the residual heat
of the engine to continue heating the vehicle
for approximately 30 minutes after the engine
has been switched off. The heating time
depends on the temperature that has been
set.
i The blower will run at a low speed
regardless of the airflow setting.
i If you activate the residual heat function
at high temperatures, only the ventilation
will be activated. The blower runs at
medium speed. Operating the climate control systems
129
Climate control
ProCarManuals.com

Display messages Possible causes/consequences and
M Solutionsb
Switch Off Lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X
Turn the light switch to Ã. Adaptive Highbeam
Assist Inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Highbeam
Assist Currently
Unavailable See
Operator's Manual Adaptive Highbeam Assist is deactivated and temporarily
inoperative. Possible causes are:
R
the windshield in the camera's field of vision is dirty.
R visibility is impaired due to heavy rain, snow or fog.
X Clean the windshield.
If the system detects that the camera is fully operational again,
the Adaptive Highbeam Assist Now Available message is
displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
M Solutions+
Check Coolant
Level See
Operator's Manual The coolant level is too low.
!
Avoid making long
journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
X Add coolant, observing the warning notes before doing so
(Y page 269).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. ? The fan motor is faulty.
X
At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic.212
Display messages
On-board computer and displays
ProCarManuals.com

Checking and adding other service
products
Checking coolant level G
WARNING
The engine cooling system is pressurized,
particularly when the engine is warm. When
opening the cap,
you could be scalded by hot
coolant spraying out. There is a risk of injury.
Let the engine cool down before opening the
cap. Wear eye and hand protection when
opening the cap. Open the cap slowly half a
turn to allow pressure to escape.
! The coolant may only be checked and
corrected when the engine is cool (coolant
temperature below 104 ‡ (40 †).
Checking the coolant when the coolant
temperature is above 104 ‡ (40 †) may
result in damage to the engine or to the
engine cooling system. Example
X
Park the vehicle on a level surface.
Only check the coolant level when the
vehicle is on

a level surface and the engine
has cooled down.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 135).
X Check the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
104 ‡ (40 †).
X Turn the SmartKey to position
0 (

Y page 135) in the ignition lock. X
Slowly turn cap : half a turn counter-
clockwise to allow excess pressure to
escape.
X Turn cap : further counter-clockwise
and
remove it.
If the coolant is at the level of marker bar
= in the filler neck when cold, there is
enough coolant in coolant expansion
tank ;.
X If necessary, add coolant that has been
tested and approved by Mercedes-Benz.
X Replace cap : and turn

it clockwise as far
as it will go.
For further information on coolant, see
(Y page 333).
Adding washer fluid to the windshield
washer system/headlamp cleaning
system G
WARNING
Windshield washer concentrate is highly
flammable. If it comes into contact with hot
engine components or the exhaust system it
could ignite. There is a risk of fire and injury.
Make sure that no windshield washer
concentrate is spilled next to the filler neck. Example
X
To open: pull cap : upwards by the tab.
X Add the premixed washer fluid.
X To close:
press cap :
onto the filler neck
until it engages. Engine compartment
269
Maintenance and care Z
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