Switching On; Heating Mode - Webasto Air Top Evo 40 Series Service Manual

3.2

Switching On

Switch on heater.
Set the control element to the required temperature.
The starting process begins when the room temperature is below the set point temperature.
Note: If the room temperature is above the selected set point temperature, only the drive motor with the combustion
and heating air fan runs. When an external room temperature sensor is connected, the drive unit does not run.
Before starting, a plausibility test of the temperature sensors is carried out and the function of the exhaust-temperature
flame monitor is checked. If the flame monitor now reports "light", the system will attempt to cool the flame monitor for
up to 100 seconds. If the flame monitor still reports "light" the control unit will suffer a fault lock-out. Also see 3.8
Fault Switch-Off.
Start
When the heater is switched on the operating display will be lit and the glow plug will be switched on (cycled). The drive
motor with the combustion and heating air fan is adjusted to approx. 50 % of the maximum speed.
After approximately 40 seconds, the fuel pump is put into operation and flame formation begins. To improve the starting
quality, the fuel pump and the drive unit are controlled with different frequencies and speeds.
After a further 80 to 120 seconds, the glow plug will be switched off and the existence of the flame established.
Automatic restart
If the flame monitor does not find a flame, the starting procedure will be repeated. The glow plug will be switched on
again (cycled). The drive motor with the combustion and heating air fan is adjusted to approx. 50 % of the maximum
speed.
After approximately 40 seconds, the fuel pump is put into operation and flame formation begins.
After a further 80 to 120 seconds the glow plug will be switched off and the existence of the flame established.
If the heater has again failed to ignite properly, then it will be shut down using a fault slow down procedure at maximum
speed after approximately 240 seconds and will suffer a fault lock-out.
Note: After restarting, a fault lock-out of the heater is carried out. To reset the fault, switch the heater off briefly (at least
2 seconds) and then on again.
3.3

Heating Mode

While the heater is operating, the combustion gases pass through the heat exchanger. In the process, the combustion
heat is given off to the walls of the heat exchanger, absorbed by the cold air transported by the heating air fan and
routed into the vehicle interior.
The temperature of the cold air intake is measured by a room temperature sensor in the control unit or an external room
temperature sensor. If the measured temperature is less than is set on the control element, the heater output increases to
the maximum heating capacity.
Air Top Evo 40 / Air Top Evo 55 Service Manual
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