AIRTRONIC / AIRTRONIC M. Manual - part 8

29

Operation and function

4

Operating instructions

The heater is operated by a control element.
Detailed operating instructions are enclosed with the
control unit.

The workshop / garage installing the heater will issue
you with the operating instructions.

Important instructions for operation

Safety checks before the start
After a lengthy period of non-use (summer months)
check that all parts fit securely (tighten screws where
necessary).
Check the fuel system visually for any leaks.

Heating at high altitudes
When using the heater at high altitudes, please note:

• Heating at altitudes up to 1500 m:

– Unlimited heating possible.

• Heating at altitudes over 1500 m – 3000 m:

– Heating is possible for short periods at this altitude

(e.g. driving over a mountain pass or taking a
break in a journey).

– During longer stays, e.g. winter camping, the fuel

supply must be adjusted to the altitude. This can
be done by installing an air pressure sensor. The
air pressure sensor is included in the Altitude kit -
Order No. 22 1000 33 22 00.

Heaters suitable for high altitudes are labelled with
“H-Kit” on the side nameplate.

Initial commissioning

The following points are to be checked by the
company installing the heater during initial
commissioning.

• After installation of the heater, the coolant circuit

and the whole fuel supply system must be vented
carefully. Comply with the instructions issued by the
vehicle manufacturer.

• During the trial run of the heater, check all water and

fuel connections for leaks and firm fitting.

• If the heater shows a fault during operation, find

and eliminate the cause of the fault using a
diagnosis unit.

Please note!

Please note!

During the initial start-up of the heater, odours can be
produced for a short time. This is fully normal during
the first few minutes of operation and does not
indicate a malfunction in the heater.

Please note!

30

Description of functions

Switching on

When the heater is switched on, the control lamp in
the control element lights up.
The glow plug is switched on and the fan starts at
low speed.

If there is still too much residual heat in the heat
exchanger from when the heater was last used, firstly
only the fan starts up (cold blowing).
Once the residual heat has been cleared, the heater
starts.

Starting Airtronic

After approx. 65 seconds the fuel supply starts and
the fuel / air mixture in the combustion chamber
ignites.
Once the combined sensor (flame sensor) has
detected the flame, the glow plug is switched off after
60 seconds. The heater is now in standard operation.

Starting Airtronic M

After approx. 60 seconds the fuel supply starts and
the fuel / air mixture in the combustion chamber
ignites.
After the flame sensor has detected the flame, the
glow plug is switched off after approx. 90 sec. The
heater is now in standard operation.
After another 120 seconds, the heater has reached
the “POWER” stage (maximum fuel quantity, maximum
fan speed).

Temperature selection with the control element

The control can be used to preselect an interior
temperature.
The resulting temperature can be within the range of
+10 °C to +30 °C and depends on the selected
heater, on the size of the space to be heated and on
the prevailing outdoor temperature.
The setting to be selected at the control is an
empirical value.

Operation and function

4

Please note!

Control in the heating mode

During the heating mode, the room temperature or the
temperature of the sucked in heating air is constantly
measured.
If the temperature is higher than the temperature
selected on the control element, the heater starts to
regulate its output. There are 4 control stages so that
the outflow of heat produced by the heater can be
adjusted finely to the heating requirements. Fan speed
and fuel quantity correspond to the particular control
stage.
If the set temperature is still exceeded in the smallest
control stage, the heater goes to the “OFF” stage with
the fan running on for approx. 4 minutes to cool off.
Then the fan continues at minimum speed (circulation
mode) or is switched off (fresh air mode) until the
heater is started again.

Ventilating mode

In the ventilating mode, first the changeover switch
“heating / venting” has to be activated and then the
heater is switched on.

Switching off

When the heater is switched off, the control lamp
goes off and the fuel supply is switched off.
The fan runs on for approx. 4 minutes to cool down.
While the fan is running on, the glow plug is switched
on for approx. 40 seconds to clean.
Special case:
If no fuel has been supplied or if the heater is in the
“OFF” stage until it is switched off, the heater is
stopped without any after running.

31

Do not switch the heater off and on again more
than twice.

Forced shutdown in ADR / ADR99 mode
(only for diesel heaters)

In vehicles for the transport of dangerous goods
(e.g. tanker trucks), the heater must be switched off
before the truck drives into a danger area (refinery,
fuel service station, etc.).
Failure to comply results in the heater switching off
automatically when:
• The vehicle engine is switched off.
• An additional unit is started up (e.g. auxiliary drive

for unloading pump etc.).

• A vehicle door is opened (ADR99 regulation,

only in France).

The fan then runs on for max. 40 seconds.

Control and safety devices

• If the heater does not ignite within 90 seconds after

starting the fuel pump, the start is repeated. If the
heater still does not ignite after another 90 seconds
of pumping fuel, the heater is switched off, i.e. the
fuel supply is off and the fan runs on for approx.
4 minutes.

• If the flame goes off by itself during operation, the

heater is restarted. If the heater does not ignite
within 90 seconds after the fuel pump has started,
or ignites and goes off again within 15 minutes, the
heater is switched off, i.e. the fuel supply is off and
the fan runs on for approx. 4 minutes.
This status can be remedied by briefly switching off
and on again.
Do not repeat the switching off/on routine more
than twice.

• In the case of overheating, the combined sensor

(flame sensor / overheating sensor) triggers, the
fuel supply is interrupted and the heater switched
off. Once the cause of the overheating has been
eliminated, the heater can be re-started by
switching off and on again.

• If the lower or upper voltage limit is reached, the

heater is switched off after 20 seconds.

• The heater does not start up when the glow plug is

defect or when the electric lead to the dosing pump
is interrupted.

• If the combined sensor (flame sensor / overheating

sensor) is defect or the electric lead interrupted, the
heater starts up and is then switched off again
during the start phase.

• The speed of the fan motor is monitored

continuously. If the fan motor does not start up or if
the speed deviates by more than 10%, the heater is
switched off after 30 sec.

• When the heater is switched off, the glow plug is

switched on for 40 seconds (after-glowing) while the
fan runs on to clean off any combustion residues.

Operation and function

4

Please note!

Emergency shutdown – EMERGENCY OFF
If an emergency shutdown – EMERGENCY OFF –
is necessary during operation, proceed as follows:
• Switch the heater off with the control or
• pull the fuse out or
• disconnect the heater from the battery.

32

Electrical system

5

Heater wiring

Caution!

Safety instructions for wiring the heater!
The heater is to be connected up electrically
according to the EMC directives.
EMC can be affected if the heater is not connected
up correctly. For this reason, comply with the following
instructions:

• Ensure that the insulation of electrical cables is not

damaged. Avoid: chafing, kinking, jamming or
exposure to heat.

• In waterproof connectors, seal any connector

chambers not in use with filler plugs to ensure they
are dirt-proof and water-proof.

• Electrical connections and ground connections must

be free of corrosion and firmly connected.

• Lubricate connections and ground connections

outside the heater interior with contact grease.

Comply with the following when wiring the heater and the
control element:
• Electrical leads, switchgear and controllers must be

arranged in the vehicle so that they can function
perfectly under normal operating conditions
(e.g.heat exposure, moisture etc.).

• The following cable cross sections are to be used

between the battery and heater. This ensures that
the max. tolerable voltage loss in the cables does
not exceed 0.5 V for 12 V or 1 V for 24 V rated
voltage.
Cable cross sections for a cable length of:
– up to 5 m (plus cable + minus cable) =
   cable cross section 4 mm²
– from 5 to 8 m (plus cable + minus cable) =
   cable cross section 6 mm²

• If the plus cable is to be connected to the fuse box

(e.g. terminal 30), the vehicle cable from the battery
to the fuse box must be included in rating the overall
cable length and possibly re-dimensioned if
necessary.

• Insulate unused cable ends.

Please note!