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122Climate controlMaintenanceAir intake
The air intake in front of the
windscreen in the engine
compartment must be kept clear to
allow air intake.
Remove any leaves, dirt or snow.
Pollen filter
The pollen filter cleans dust, soot,
pollen and spores from the air
entering the vehicle through the air
intake.
Air conditioning regular
operation
In order to ensure continuously
efficient performance, cooling must
be operated for a few minutes once a
month, irrespective of the weather
and time of year. Operation with
cooling is not possible when the
outside temperature is too low.
Service For optimal cooling performance, it is recommended to annually check the
climate control system, starting
three years after initial vehicle
registration, including:
● functionality and pressure test
● heating functionality
● leakage check
● check of drive belts
● cleaning of condenser and evaporator drainage
● performance check
Page 160 of 231

158Driving and operatingTrailer hitch
General information
Only use towing equipment that has
been approved for your vehicle.
Entrust retrofitting of towing
equipment to a workshop. It may be
necessary to make changes that
affect the cooling system, heat
shields or other equipment.
The bulb outage detection function for trailer brake light cannot detect a
partial bulb outage, e.g. in case of four
times five watt bulbs, the function only detects lamp outage when only a
single five Watt lamp remains or none
remain.
Fitting of towing equipment could
cover the opening of the towing eye.
If this is the case, use the coupling ball bar for towing. Always keep the
coupling ball bar in the vehicle when
not in use.Driving characteristics and
towing tips
Before attaching a trailer, lubricate
the coupling ball. However, do not do
so if a stabiliser, which acts on the coupling ball, is being used to reduce
snaking movements.
For trailers with low driving stability
and caravan trailers with a permitted
gross vehicle weight of more than
1000 kg a speed of 50 mph must not
be exceeded; the use of a stabiliser is
recommended.
If the trailer starts snaking, drive more
slowly, do not attempt to correct the
steering and brake sharply if
necessary.
When driving downhill, drive in the
same gear as if driving uphill and
drive at a similar speed.
Adjust tyre pressure to the value
specified for full load 3 217.Trailer towing
Trailer loadsThe permissible trailer loads are
vehicle and engine-dependent
maximum values which must not be
exceeded. The actual trailer load is
the difference between the actual
gross weight of the trailer and the
actual coupling socket load with the
trailer coupled.
The permissible trailer loads are
specified in the vehicle documents. In general, they are valid for gradients
up to max. 12%.
The permitted trailer loads apply up to
the specified incline and up to an
altitude of 1000 metres above sea
level. Since engine power decreases
as altitude increases due to the air
becoming thinner, therefore reducing
climbing ability, the permissible gross train weight also decreases by 10%
for every 1000 metres of additional
altitude. The gross train weight does
not have to be reduced when driving
on roads with slight inclines (less than
8%, e.g. motorways).
Page 166 of 231
164Vehicle carewebsite, where legally required. Only
entrust this work to an authorised
recycling centre.
Gas vehicles must be recycled by a
service centre authorised for gas
vehicles.Vehicle checks
Performing work9 Warning
Only perform engine compartment
checks when the ignition is off.
The cooling fan may start
operating even if the ignition is off.
9 Danger
The ignition system and Xenon
headlights use extremely high
voltage. Do not touch.
Bonnet
Opening
Pull the release lever and return it to
its original position.
Page 168 of 231
166Vehicle care
We recommend the use of the same
grade of engine oil that was used at
last change.
The engine oil level must not exceed
the MAX mark on the dipstick.
The engine oil filler cap is located on
the camshaft cover.Caution
Overfilled engine oil must be
drained or suctioned out.
Capacities 3 216.
Fit the cap on straight and tighten it.
Engine coolant The coolant provides freeze
protection down to approx. -30 °C. In
northern countries with very low
temperatures the factory filled coolant
provides frost protection down to
approx. -40 °C.
Caution
Only use approved antifreeze.
Coolant levelCaution
Too low a coolant level can cause engine damage.
If the cooling system is cold, the
coolant level should be above the
filling line mark. Top up if the level is
low.
Page 181 of 231
Vehicle care179No.Circuit1Sunroof2Exterior mirrors3–4–5Electrical brake control module6Intelligent battery sensor7–8Transmission control module9–10Headlight levelling11Rear window wiper12Heated rear window13Headlight actuator (left hand)14Heated exterior mirrors15–16Seat heating17Transmission control moduleNo.Circuit18Engine control module19Fuel pump20–21Cooling fan22–23Ignition coil/Engine control
module24Washer pump25Headlamp actuator (right hand)26Engine control sensors27–28Ignition29Ignition30Exhaust system31Left-hand high beam32Right-hand high beam33Engine control module34HornNo.Circuit35Air conditioning system36Front fog lamp
J-cases Fuses
No.Circuit1Electrical brake control module2Front wiper3Power module4Power terminal of instrument
panel fuse box5–6Fuel heater7–8Cooling fan9Cooling fan10Engine control module/Glow
plug11Starter
Page 191 of 231

Vehicle care189
The legally permissible minimum
tread depth (1.6 mm) has been
reached when the tread has worn
down as far as one of the tread wear
indicators (TWI). Their position is
indicated by markings on the
sidewall.
If there is more wear at the front than
the rear, swap round front wheels and rear wheels. Ensure that the direction
of rotation of the wheels is the same
as before.
Tyres age, even if they are not used.
We recommend tyre replacement
every six years.
Changing tyre and wheel
size
If tyres of a different size than those
fitted at the factory are used, it may be necessary to reprogramme the
speedometer as well as the nominal
tyre pressure and make other vehicle modifications.
After converting to a different tyre
size, have the label with tyre
pressures replaced.9 Warning
Use of unsuitable tyres or wheels
may lead to accidents and will
invalidate the vehicle type
approval.
Wheel covers
Wheel covers and tyres that are
factory-approved for the respective
vehicle and comply with all of the
relevant wheel and tyre combination
requirements must be used.
If the wheel covers and tyres used are
not factory-approved, the tyres must
not have a rim protection ridge.
Wheel covers must not impair brake
cooling.9 Warning
Use of unsuitable tyres or wheel
covers could lead to sudden
pressure loss and thereby
accidents.
Vehicles with alloy wheels: When
mounting steel wheels with alloy
wheel nuts, e.g. when changing to
winter tyres, the wheel covers cannot
be attached to the steel wheels.
Tyre chains