Function Description - Webasto Air Top Evo 3900 Workshop Manual

Air Top Evo 3900/5500
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 tempera-
ture between approx. 5 °C and 35 °C) and to reset the heat-
er after a fault.
In addition, other comfort functions (Eco, Normal, Plus, Ven-
tilation, 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).
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 Operating modes of heater
The Air Top Evo 3900 and Air Top Evo 5500 can be activated
with the heater controls rotary selector, combination timer
or MC04/05.
3.2.1 Comfort heating
Comfort functions (Eco, Plus, Altitude Compensation and
Ventilation) can be selected manually with the MC04/05
heater control. They can be implemented in special heater
variants.
3.2.2 Eco mode
This is a specific energy-saving mode. The heater will oper-
ate at approx. 70 % of its maximum output. This reduces
both fuel and electrical consumption. This mode is especially
used for maintenance heating.
3.2.3 Plus mode
The heater is operated for a limited time at an increased
heating capacity of 110 % to enable fast heat-up. When the
set temperature is reached, the heater automatically switch-
es back to its normal capacity. The increased heating capac-
ity can also be switched on during ongoing operation if
necessary (sudden drop in temperature due, for example, to
opening the cab door). The maximum duration of the in-
creased heating capacity is 60 minutes for the
Air Top Evo 3900 and 30 minutes for the Air Top Evo 5500
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(continuously or in time increments).
3.2.4 Altitude compensation
With the altitude compensation function, optimum com-
bustion operation at over 1,200 m up to 2,200 m above sea
level is achieved (the air becomes thinner, the CO
rises, the fan speed increases and the heating capacity and
metering pump frequency are reduced). In special variants,
a pressure sensor assumes the automatic altitude control.
3.2.5 Ventilation
The fan speed for the fresh air supply is adjusted with the
temperature selector.
IMPORTANT
If the heater is in combustion operation, an approx.
3 minute long cooling phase is carried out before ventilation
is activated.
3.3 Switching on
Set the control element to the required temperature.
If the hot air temperature is lower than the nominal temper-
ature the heater will start
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 an external
temperature sensor is used (not with special variants).
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 re-
ports "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.
Function Description
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