Maximum heat output and the fastest possible defrosting of the windows are possible only when
the engine is running. Do not start your journey until you have good visibility.
To help ensure good visibility, make sure that you use the air conditioning system and the rear
window heating correctly.
Auxiliary heater and ventilation
Introduction
This chapter contains information on the followingsubjects:
Switching the auxiliary heater and ventilation on and off
Programming the auxiliary heater and ventilation
Remote control
The auxiliary heater and ventilation system can be used to heat the vehicle interior in the winter and
ventilate it in the summer. It is able to clear ice, condensation and a thin layer of snow from the
windscreen. The auxiliary heater is supplied with fuel from the vehicle fuel tank and can be operated
when the vehicle is stationary with the ignition switched off. The auxiliary ventilation system is
powered by the 12-volt vehicle battery.
Auxiliary heater exhaust system
The emissions generated by the auxiliary heater are discharged via an exhaust pipe underneath the
vehicle. The exhaust pipe must not be blocked by snow, mud or other objects.
WARNING
Among other things, the emissions from the auxiliary heater contain carbon monoxide, which is an
odourless and colourless poisonous gas. Carbon monoxide can cause people to lose consciousness. It
can also cause death.
Never switch on the auxiliary heater when the vehicle is in unventilated or closed rooms nor let the
auxiliary heater run in unventilated or closed rooms.
Never program the auxiliary heater so that it is switched on and runs in unventilated or closed
rooms.
WARNING
Parts of the auxiliary heater exhaust system become very hot. This can cause fires.
Park the vehicle so that no part of the exhaust system can come into contact with any inflammable
material underneath the vehicle, e.g. dry grass.
Food, medicine and other items that are sensitive to heat or cold could be either damaged or
rendered useless by the air flowing out of the vents.
Never leave food, medicines or other temperature-sensitive objects in front of the vents.
Switching the auxiliary heater and ventilation on and off
First read and observe the introductoryinformation and safety warnings
The auxiliary heater can be operated only when the ignition is switched off. If the ignition is switched
on while the auxiliary heater is working, the auxiliary heater continues to run to provide additional
heat.
Switching on the auxiliary heater
Press the immediate heat button in the air conditioning block Front controls
OR: press the button on the remote control Remote control
OR: program the departure time Programming the auxiliary heater and ventilation
The auxiliary heater heats the vehicle interior to at least 22
The auxiliary heater will not switch on if the 12-volt vehicle battery is low or the fuel tank is empty.
Switching off the auxiliary heater manually
Press the immediate heat button in the air conditioning block Front controls
OR: press the button on the remote control Remote control
OR: touch the function button on the Infotainment system Programming the auxiliary heater
Auxiliary heater switches off automatically
When the programmed departure time is reached, or after the programmed operating period has
elapsed Programming the auxiliary heater and ventilation
When the indicator lamp lights up (fuel gauge) Fuel gauge
If the charge level of the 12-volt vehicle battery is too low 12-volt vehicle battery
The auxiliary heater runs on for a short time after it has been switched off manually or automatically
so that the remaining fuel in the system can be burnt off.
When the vehicle is at a standstill, the auxiliary heater can be activated up to three times in
succession for the maximum operating duration.
The 12-volt vehicle battery will discharge if the auxiliary heating or ventilation is run several times
over an extended period. Drive the vehicle for an appropriate distance in between in order to
recharge the 12-volt vehicle battery.
The fuel gauge indication may not be accurate (just above the reserve quantity) when the vehicle is
parked on a slope; this may restrict the function of the auxiliary heater.
The auxiliary heater may switch on automatically when the engine is started at temperatures below
+5
e date and time set in the vehicle are correct Time
Open the Auxiliary heater menu.
Touch the Set function button.
Select one of the memory locations for a Departure time.
Touch the Activate function button.
Manual air conditioning system: the programmed departure time determines the time at which
the auxiliary heater or ventilation should switch off. The point at which the heating or ventilation
process starts is determined depending on the programmed running time.
Climatronic: on the basis of the programmed departure time, the vehicle automatically
calculates the start time for heating or ventilation to the currently set temperature depending on
the outside temperature.
Press the Running time function button under Adjust in order to select the running time when the
auxiliary heater is switched on using the immediate heat button or remote control.
Checking programming
If a departure time has been activated, the LED in the immediate heat button will light up on the
Climatronic control panel for approximately 10 seconds after the ignition is switched off.
WARNING
Never program the auxiliary heating system so that is switched on and run in unventilated or
enclosed spaces. Among other things, the emissions from the auxiliary heater contain carbon
monoxide, which is an odourless and colourless poisonous gas. Carbon monoxide can cause people
to lose consciousness. It can also cause death.
Remote control
Fig. 93 Auxiliary heater: remote control (left) with battery compartment (right).
First read and observe the introductoryinformation and safety warnings
Switching on: press the button Fig. 93
The auxiliary heater is switched on when the LED on the remote control is lit up green.
Switching off: press the button Fig. 93
The auxiliary heater is switched off when the LED on the remote control is lit up red.
LED in the remote control
The LED Fig. 93
Lit up
greenThe auxiliary heater is switched on.redThe auxiliary heater is switched off.
Flashing irregularly
greenAuxiliary heater disabled: the fuel tank is nearly empty, the 12-volt vehicle battery voltage is
too low or a malfunction has occurred. Refuel and drive long enough to recharge the 12-volt vehicle
battery or visit a qualified workshop.
Flashing regularly
red or greenSwitch-on or switch-off signal has not been received. Move closer to the vehicle.
Lit up or flashing
orangeThe button cell (battery) in the remote control is weak. Replace the button cell.
Range
The remote control has a range of a few hundred metres when the button cell is fully charged.
Maintain a distanced of at least 2 metres between the remote control and the vehicle.
Avoid any obstacles between the remote control and the vehicle.
Hold the remote control with the aerial Fig. 93pointing vertically upwards.
Do not cover the aerial.
Adverse weather or a weak battery cell will significantly reduce the range.
Renewing the button cell in the remote control
The button cell in the remote control must be replaced if the indicator lamp does not light up.
Insert a suitable object, e.g. a screwdriver, in the recess on the side in the direction of the arrow
Fig. 93
Use the object to lever off the battery cover.
Slide the battery cover forwards slightly in the direction of the arrow.
Fig. 192 Battery window on the top of the 12-volt vehicle battery (illustration).
First read and observe the introductoryinformation and safety warnings
The electrolyte level of the 12-volt vehicle battery should be checked regularly in high-mileage
vehicles, in hot countries and in older 12-volt vehicle batteries. The 12-volt vehicle battery is
otherwise maintenance-free.
Vehicles with an auxiliary heater Auxiliary heater and ventilationare fitted with special vehicle
batteries. The electrolyte level of these 12-volt vehicle batteries cannot be checked for technical
reasons. Go to a qualified workshop to have the 12-volt vehicle battery checked.
Preparations
eparing the vehicle for working in the engine compartment In the engine compartment
In the engine compartment
Checking the electrolyte level (12-volt vehicle batteries with battery window)
e for you to clearly see the colour indicator in the round
battery window on the top of the 12-volt vehicle battery Fig. 192(arrow). Never use naked
flames or glowing objects as a light source.
s according to the electrolyte level in the
12-volt vehicle battery.
Light yellow or without colourThe electrolyte level of the 12-volt vehicle battery is too low. The 12-
volt vehicle battery should be checked and replaced by a qualified workshop if necessary.BlackThe
electrolyte level of the 12-volt vehicle battery is correct.
WARNING
Any work on the 12-volt vehicle battery can cause serious chemical burns, explosions and electric
shocks.
-volt vehicle battery
-volt vehicle
battery.
e cable and then the negative cable
Various indicator lamps may light up after the 12-volt vehicle battery has been connected and the
ignition is switched on. They will go out when you drive a short distance at a speed of approximately
15 20 km/h (10 12 mph). If the indicator lamps remain lit up, the vehicle should be checked by a
qualified workshop.
If the 12-volt vehicle battery was disconnected for an extended period, the system may not able to
calculate or correctly display the time when the next service is due Instrument cluster
the maximum permissible service intervals Service
Automatic switch-off for electrical consumers
The intelligent vehicle electrical system management function automatically implements a range of
measures to prevent the 12-volt vehicle battery from discharging under high loads:
power supply to the 12-volt socket and the cigarette lighter may be interrupted temporarily
while the engine is being started.
The vehicle electrics management system cannot always prevent the 12-volt vehicle battery from
being discharged, for example if the ignition is left on over a long period with the engine off or the
side lights or parking lights are left on over a long period of time.
12-volt vehicle battery is discharged
gnition is switched on.
Auxiliary heater and ventilation
WARNING
Incorrectly mounting the battery and using incorrect 12-volt vehicle batteries can cause short
circuits, fire and serious injuries.
-free and leak-proof 12-volt vehicle batteries that have the same
properties, specifications and dimensions as the factory-fitted 12-volt vehicle battery.
WARNING
A highly explosive mixture of gases is given off when the 12-volt vehicle battery is being charged.