Repair manual

5. Troubleshooting
5.1 General
This section describes troubleshooting procedures for
the Air Heater Air Top 2000 and Air Top 2000 Diagnosis.
A malfunction in air heaters Air Top 2000 Diagnosis out-
puts an error code to the display of the combination or
standard timer. When equipped with a control element
the operating indicator flashes. In addition a heater chec-
kout may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).
CAUTION
Troubleshooting requires profound knowledge about
structure and theory of operation of heater components
and may only be performed by skilled personnel.
In cases of doubt refer to Sections 2 or 3 for functional
interrelations.
NOTE
Only for TRS operation
After a TRS switch-off or power application by vehicle
main power switch operation and the control element to
“ON”, the control unit will be in “error lockout”.
Prior to reactivation the control element must be set to
“OFF” or the instant heat switch on the combination or
standard timer be operated.
CAUTION
Troubleshooting is normally limited to the isolation of
defective components.
The following causes for trouble are not considered and
should always be checked for to exclude them as cause
for trouble:
corrosion on connector
loose contact on connector
wrong crimping on connector
corrosion on electrical wiring and fuses
corrosion on battery terminals
If individual components are checked, the control unit
electrical connections must be disconnected.
After any correction of a failure a functional test has to
be performed in the vehicle.
5.2 General Failure Symptoms
The following table (Fig. 501) lists the possible failure
symptoms.
501
Fig. 501 General Failure Symptoms
Failure Symptom Probable Cause Remedy
Air heater switches No combustion after start or repeat Switch off heater momentarily and
off automatically start switch on
once again
Flame extinguishes during Switch off heater momentarily and
operation switch on
once again
Heater overheats Check heat air ducting for
Operation indication flashes obstructions, allow heater to cool
down, switch off heater momentarily
and switch on
once again
Vehicle electrical Charge battery
system voltage too low Switch off heater momentarily and
switch on
once again
Heater expels black fumes Combustion air and/or Check combustion and exhaust
exhaust ducting blocked ducting for obstructions
Air Top 2000 5 Troubleshooting