Webasto Air Top 2000 ST D Service And Repair Manual - page 13
Webasto Product N.A., Inc.
10
www.techwebasto.com
FUNCTIONAL DESCRIPTION
AIR TOP 2000 ST
3.5
C
ONTROL
P
AUSE
After the temperature set on the control element has
been reached, the heat output is reduced. The speed of
the heating and combustion air blower and the delivery
rate of the metering pump are reduced.
If, at minimum heat output, the intake temperature set
on the control element is exceeded, the metering pump
is shut down and the combustion process ended. To
burn off the flame properly the blower speed falls after
20 seconds to low-fire rate speed and then returns to the
initial speed after 15 seconds, after which it falls to the
control pause speed in 3 minutes, where it remains for
the entire control pause.
The control pause speed on boat heaters is 0.
If the temperature set on the control element is not
observed at the temperature sensor, the heater will
restart.
NOTE: Changes to the setting on the control
element are implemented by the control unit
and heater after a delay.
3.6
S
WITCH
O
FF
When the heater is switched off, the ON control LED on
the control element goes out. If no fuel has been
transported or if the heater is in the control pause, the
heater is switched off immediately without a slow down
time.
If the fuel transport has been started, it is ended
immediately when the heater is switched off. The heater
is switched off using the same method as the transition
from control mode to control pause. The device is then
switched off automatically.
NOTE: The heater may be switched on again
during the slow down time. In this case the
slow down time is completed and the heater is
then restarted.
3.7
F
AULT
L
OCK
-
OUT
The control unit has identified errors on individual heater
components and faults during the starting procedure and
in operation. The heater is switched off and goes into
fault lock-out if the following conditions occur:
•
No repeated or incorrect start
•
Temperature sensor defective
•
Overheating sensor interrupt or short circuit
•
Overheating sensor installed incorrectly
•
Glow pin interrupt or short circuit
•
Blower motor overload or blocked or short circuit or
break
•
Flame sensor interrupt or short circuit
•
Error in the metering pump or overheating guard
circuit (start phase only)
•
Under voltage below 10.5 V / 21 V for longer than
20 seconds
•
Over voltage above 16 V / 32 V for longer than 6
seconds
•
Control module defective
The fuel supply is stopped if the heater overheats. The
heater continues to run in the same way as if it is
switched off manually. After it stops the control unit will
be set to fault lock-out. After the slow-down phase the
control module is set to fault lock-out if the overheating
counter is greater than the value programmed in the
data record (currently 20).
The overheating is indicated by the indicator flashing
10 times.
Rectify the cause of the fault.
To reset the fault, switch the heater off briefly (at least
2 seconds) and then on again.