Ebasto Air Top Evo 3900 Workshop Manual - page 15
Air Top Evo 3900/5500
3 Function description
301
3
Function description
3.1
Control element
The control element is designed to switch the heater on
and off, adjust the required room temperature (intake
temperature between 5 °C and 35 °C) and to reset the
heater after a fault.
In addition, other comfort functions (Eco, Normal, Plus,
Ventilation, Altitude Compensation) can also be activated
with the MC04/05 heater control.
The integral green LED is designed to act
•
as an ON signal,
•
as a fault signal,
•
as service display (LED flashes).
NOTE
ADR operation:
After an operating voltage has been applied by switching
the battery isolation switch and control element to “ON”
the control unit will be set to the “Fault lock-out” position.
Before it can be restarted the control element must be set
to “OFF”.
3.2
Switch on
Set the control element to the required temperature.
If the hot air temperature is lower than the nominal tem-
perature the heater will start
NOTE
If the temperature of the hot air intake is above the set
nominal temperature, only the motor for the hot and
combustion air blower will start (control pause). Special
feature: The control pause speed is 0 rpm if boat heaters
are used.
The function of the flame sensor is checked.If the flame
sensor now reports “light”, the system will attempt to cool
the flame sensor for 60 seconds.If the flame sensor still
reports “light” the control unit will suffer a fault lock-out.If
another monitored component has suffered a fault, the
fault lock-out will take effect without any slow down time.
Start
When the heater is switched on the ON signal light will be
lit and the glow plug will be switched on (cycled). The
motor for the hot and combustion air blower will be set to
approx. 50% of its maximum speed.
After approx. 40 seconds the fuel metering pump will start
and the flame formation will begin.To improve the starting
quality the metering pump and combustion air blower are
started with different frequencies and speeds.
After a further 90 seconds the glow plus will be switched
off and the existence of the flame established.
Automatic restart
If the flame sensor does not find a flame, the starting pro-
cedure will be repeated.The glow plug will be switched on
again (cycled).The motor for the hot and combustion air
blower will be set to approx. 50% of its maximum speed.
After approx. 40 seconds the fuel metering pump will start
and the flame formation will begin.
After a further 50 seconds the glow plus will be switched
off and the existence of the flame established.
If the heater has again failed to ignite properly, the it will
be shut down using a fault slow down procedure at maxi-
mum speed after 180 seconds and will suffer a fault lock-
out.
NOTE
After a restart the heater will suffer a fault lock-out.To
reset the fault switch the heater off briefly (at least 2
seconds) and then on again.
3.3
Heating mode
Whilst the heater is operating the combustion gases pass
through the heat exchanger. During this process the com-
bustion heat is given off to the walls of the heat exchang-
er, absorbed by the hot air transported by the hot air
blower and fed into the interior of the vehicle.
The temperature of the hot air intake is measured by a
temperature sensor in the control unit or an external tem-
perature sensor. If the measured temperature is lower
than the value set on the control element, the output of the
heater is increased to maximum heat output.
To increase the burner service life when it is used
continuously the transport capacity of the metering pump
is reduced for 10 seconds every 10 minutes.
In addition, heating mode is interrupted every 8 hours in
the same way as for a control pause.
3.4
Control mode
In control mode the blower speed and the metering pump
delivery rate are dependent on the heat output. The glow
plus is switched off.