Mercedes-Benz 2013 M Class - Manual (Page 152)

Problems with the rear window defroster
Problem Possible causes/consequences and M Solutions
The 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 or interior lighting.
When the battery is sufficiently charged, the rear window
defroster is activated again automatically.
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 157).
X To activate: press the d button.
The indicator lamp in the d button lights
up.
i In the event of high pollution levels (3-
zone automatic climate control only) or at
high outside temperatures, air-
recirculation mode is automatically
activated. When air-recirculation mode is
activated automatically, the indicator lamp
in the d button is not lit.
Outside air is added after about
30 minutes.
X To deactivate: press the d button.
The indicator lamp in the d 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
cooling with air dehumidification 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 Canada.
150
Operating the climate control systems
Climate control