Fault Lock-Out - Webasto Air Top Evo 3900 Workshop Manual

Function Description
3.1.1.2. The exhaust system as well as the exhaust
pipes shall be so directed or protected to avoid any
danger to the load through heating or ignition. Parts
of the exhaust system situated directly below the fuel
tank (diesel) shall have a clearance of at least 100 mm
or be protected by a thermal shield.
3.1.2. The combustion heater shall be switched on
manually. Programming devices shall be prohibited.
3.2. EX/II and EX/III vehicles
Combustion heaters using gaseous fuels are not per-
mitted.
3.3. FL vehicles
3.3.1. The combustion heaters shall be put out of op-
eration by at least the following methods:
a)intentional manual switching off from the driv-
er's cab;
b)stopping of the vehicle engine; in this case the
heating device may be restarted manually by
the driver;
c) start-up of a feed pump on the motor vehicle
for the dangerous goods carried.
End of extract.

3.10 Fault lock-out

Errors on the various heater components and faults in the
starting process and in heating mode are identified in the
control unit. The heater is switched off and goes into fault
lock-out if the following conditions occur:
• No or incorrect start
• Temperature sensor defective
• Overheating sensor interrupt or short circuit
• Overheating sensor installed incorrectly
• Glow plug/Flame monitor interrupt or short circuit
• Fan motor overload or blocked or short circuit or
interrupt
• Error in metering pump circuit
• 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
• Overheating
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.
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).
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Air Top Evo 3900/5500
3.10.1 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. If the incorrect start counter
reaches its maximum value of 9 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. If the error counter
reaches its maximum value of 5 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 5 the heater will go into the heater lock-
out status HGV.
After a flame abort FAZ, a restart is automatically carried
out. The condition for a restart is that the heater was in the
control mode directly beforehand. During the restart the
cycle repetition counter ZWZ is increased by one. This
process is repeated until the heater either burns properly
again or the maximum value of 3 for the cycle repetition
counter has been reached.
The flame abort counter FAZ is increased by 1 when the
cycle repetition counter ZWZ has reached the maximum
value. If the flame abort counter reaches its maximum value
of 3 the heater will go into the heater lock-out status.
Automatic reset:
Following each heater start-up, the cycle repetition counter
ZWZ is set to 0. The fault counter is set to 0 after a fault-free
transition to the control mode and the flame abort counter
FAZ, overheating counter UHZ, false starting counter FSZ
and cycle repetition counter ZWZ are set to 0 after(!) fault-
free combustion operation (20 min.).