Failure Symptoms During Operation - Webasto Air Top 2000 D Service And Repair Manual

5 Troubleshooting
5.3

Failure Symptoms during Operation

The following table (Fig. 502) lists the possible failure
symptoms as they might occur during the functional
sequence of operation.
In case of malfunction the failure is to be isolated and
removed using this table. It is important to accurately
identify the failure symptom.
Should the failure symptom not be contained in this
table or the trouble not be detected under the specific
Failure Symptom
No start and no illumination
of LED on control element
No start but LED illuminates
Very low speed with no start
Motor operates momentarily
and then stops
Stoppage without run-down
Run-down after
Run-down after
Run-down after
and dosing pump does not cycle
Run-down after
Run-down after
Run-down
Stoppage without run-down
Interruption of dosing pump
cycling and max. speed for
30 sec with subsequent re-start
502
failure symptom listed, in emergencies assistance by our
service technicians may be requested
(Tel. 089 / 8 57 94 - 512).
Overheating and dosing pump failure are always indi-
cated additionally after run-down by the flashing LED of
the control element.
In all cases of trouble also a defective control unit may
be the cause should all other components turn out to be
serviceable.
shows after
....s
immediately
immediately
immediately
1
5
1
20
120
40 to 120
230
during combustion
operation
during combustion
operation
during combustion
operation
Fig. 502 Failure Symptoms during Operation
NOTE
Possible Causes
Wrong cabling, defective fuse
Fan or control unit defective or fan blocked
Control idle operation: wrong manual control (selected
temperature is below air intake temperature)or wrong
integration (excessive air intake temperature)
Glow plug or flame sensor short or open circuit or
control unit defective
Fan motor obstructed, binding
Flame detection erroneous
Voltage to control unit too low
Cabling to dosing pump, pump itself or overheat
protection defective
Intermittent disconnect of connection to dosing pump
or to overheat protection
No flame: wrong fuel supply quantity, defective or slow
fan, coked burner (in particular pilot flame outlet bore),
combustion air/exhaust ducting obstructed or heat
exchanger coked, dosing pump seized
Overheating or
voltage too low or
component error (flame sensor, glow plug,
overheat sensor, dosing pump, burner) or
no fuel supply or obstructed combustion air/exhaust
ducting
Fan motor failure or seizure
Flame-out by gas bubbles in fuel delivery or strong
wind against exhaust outlet or defective no-flame
detection
Air Top 2000