Troubleshooting - Webasto Air Top Evo 3900 Workshop Manual

Air Top Evo 3900/5500
5

Troubleshooting

5.1 General
This section describes how to identify and deal with errors
on the Air Top Evo 3900 and Air Top Evo 5500 heaters.
If a fault occurs, an error code will be output in the display
of the combination timer.
If the heater has a control element, the ON control light will
flash.
In addition the heater can be checked using a personal
computer (see PC heater diagnostic operating manual).
IMPORTANT
Troubleshooting work demands precise knowledge of the
structure and theory of operation of the various
components and must be carried out by trained personnel
only. If in doubt, refer to sections 2 and 3 for a description
of how the functions interact.
For ADR mode only
After an ADR shut-down or an operating voltage has been
applied by switching the main vehicle 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" or the Immediate heat
button pressed on the combination timer.
Error symptom
Heater unit cuts out automatically
Heater unit emits black smoke
NOTE
Possible cause
No combustion after start and restart
ON indicator flashes
Flame extinguishes during
operation
ON indicator flashes
Heater unit overheats ON indicator flashes
Vehicle voltage too low
ON indicator flashes
Combustion air and/or exhaust system
blocked
Fig. 501 General error symptoms
IMPORTANT
The troubleshooting guide is restricted to the localisation
of defective components.
The following potential sources of malfunctions are not
taken into account and should always be checked so that
they can then be excluded as the cause of the particular
fault:
• Corroded plugs
• Loose plug contacts
• Poor crimp contacts on plugs
• Corroded cables and fuses
• Corroded battery terminals
If you wish to check individual components, the electrical
plug connectors on the control unit must be disconnected.
Conduct a function test in the vehicle after rectifying each
fault.
5.2 General error symptoms
The following table (Fig. 501) lists the possible error
symptoms.
Remedy
Switch heater off and then on again
Switch heater off and then on again
Check that the hot air system is clear,
allow the heater to cool, switch heat off
briefly and then on again
Charge battery
Switch heater off and then on again
Check that the combustion air and
exhaust systems are clear
5 Troubleshooting
501