Webasto HL 90 Owner's Manual - page 15
HL 90
5 Troubleshooting
501
5
Troubleshooting
5.1
General
This section describes troubleshooting procedures for
the heater HL90.
CAUTION
Troubleshooting requires profound knowledge about
components and their theory of operation and may only
be performed by trained personnel.
In case of doubt functional interrelations may be derived
from Sections 2 and 3.
CAUTION
Troubleshooting is normally limited to the isolation of
defective components.
The following possible causes for trouble have not been
taken into consideration and must always be excluded
as a possible cause for malfunction:
check fuel, combustion air and
exhaust lines for obstructions
corrosion on connectors
loose contacts on connectors
wrong crimping on connectors
corrosion on wiring and fuses
corrosion on battery terminals
For individual component checks the electrical
connections on the control unit have to be disconnected.
After any fault correction a functional checkout in the
vehicle has to be performed.
5.2
General Fault Symptoms
The following table (Fig. 501) lists possible fault
symptoms of general nature.
Fig. 501 General Failure Symptoms
Symptom
Probable Cause
Remedy
Heater switches off
automatically
No combustion after start and
restart
Flame-out during operation
Heater overheats
Dosing pump does not deliver fuel
Vehicle’s electrical system voltage
too low
Switch off heater momentarily and
switch on once again
Switch off heater momentarily and
switch on once again
Check combustion air ducting for
obstructions,
allow heater to cool down,
reset temperature limiter,
Check dosing pump
Charge battery
Heater is immediately
in run-down
Replace sensor defective
Replace flame sensor
Heater develops
black smoke
Combustion air and/or exhaust
ducting clogged
Check combustion air and exhaust
ducting for obstructions
HL 90
Press reset pin on
temperature limiter