Fault Lock-Out; Error Monitoring; Switching Off - Webasto Type Air Top 2000 ST B Workshop Manual

Description of operation
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 exceeded at
the temperature sensor, the heater will restart.
Changes to the setting on the control element are
implemented by the control unit and heater after a delay.
3.6

Switching off

When the heater is switched off the ON control LED on the
control element goes out. If no fuel has been transported
yet or if the heater is in the control pause, the heater is
switched off immediately without a run-on period.
If the fuel transport has been started it is ended 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.
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 Heater functions when installed in
ADR vehicles
Only for Air Top Evo 2000 ST diesel heaters that are installed
in vehicles for transporting hazardous substances (ADR).
If the heater is switched off using the control element the
slow down time remains unchanged.
A brief slow down time (max. 40 seconds) is started
automatically if
• the vehicle's engine is switched off
• a transport device is started.
After an ADR shut down process the control unit is in the
"Fault lock-out" position. Before it can be restarted, the
control element must be set to "OFF".
3.8

Fault lock-out

Errors on the various heater components and faults in the
starting process and in operation are identified in the
control unit. The heater is switched off and goes into fault
lock-out if the following conditions occur:
302
NOTE
NOTE
NOTE
• No repeated or incorrect start
• Temperature sensor defective
• Overheating sensor interrupt or short circuit
• Overheating sensor installed incorrectly
• Glow plug interrupt or short circuit
• Fan motor overload or blocked or short circuit or
interrupt
• Flame monitorinterrupt or short circuit
• Error in the metering pump or overheating guard circuit
(start phase only)
• Undervoltage below 10.5 V/21 V for longer than 20
seconds
• Overvoltage above 16 V/32 V for longer than 6 seconds
• Control unit 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 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 on and off briefly (at
least 2 seconds).

3.8.1 Error monitoring

The overheat, incorrect start and flame failure errors are
counted and cause the heater to suffer a fault lock-out after
an error has occurred the maximum number of times.
The incorrect start counter FSZ is incremented by 1 each
time the heater fails to start and decremented by 1 each
time it starts correctly, but does not fall below 0. If the
incorrect start counter reaches its maximum value of 7 the
heater will go into the heater lock-out status HGV.
The error counter SZ is incremented by 1 each error for
which there is no separate counter. The error counter is
reset to 0 at the start of control mode. If the error counter
reaches its maximum value of 10 the heater will go into the
heater lock-out status HGV.
The overheating counter ÜHZ is incremented by 1 each time
the heater overheats. If the overheating counter reaches its
maximum value of 20 the heater will go into the heater lock-
out status HGV.
The flame failure counter FAZ is increased by 1 each time the
flame fails during heating mode. The counter is
decremented by 1 each time the heater is in control mode.
Air Top 2000 ST