Webasto Thermo 90 Workshop Manual

Thermo 90 5 Troubleshooting
501
5 Troubleshooting
5.1 General
This section describes troubleshooting procedures for the
Water Heater Thermo 90 and Thermo 90 S.
CAUTION
Troubleshooting requires profound knowledge about
str
ucture 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
inte
rrelations.
CAUTION
Troubleshooting is normally limited to the isolation of
de
fective components.
The following defects are not included in the trouble
shoo
ting procedures. Before troubleshooting, check for
and eliminate these defects:
• corrosion on connector
• loose contact on connector
• wrong crimping on connector
• corrosion on electrical wiring and fuses
• corrosion on battery terminals
After any correction of a failure a functional test has to be
pe
rformed in the vehicle; before switch the heater off and
on again.
5.2 General Failure Symptoms
The following table (Fig. 501) lists possible, general failure
symptoms.
Fig. 501 General Failure Symptoms
NOTE
In many cases the probable cause of failure may be the
bur
ner. Perform a visual inspection according to 5.4.
Failure Symptom Failure Symptom Remedy
Heater switches
off automatically
No combustion after start or repeat
st
art
Control unit goes to error lock-out.
Switch heater off and on again
Flame extinguishes during operation If a no-heating condition persists
con
tact Webasto service agent
Heater overheats due to lack/loss of
cool
ant
Replenish coolant.
After cool-down of unit, push button of
temp
erature limiter before reactivation
or replace temperature limiter
Low voltage condition for more than
20 seconds
Check fuses, connections, and charge
of ba
ttery.
Switch-off caused by temperature
limiter
After cool-down of unit, push button
of temperature limiter before
r
eactivation or replace temperature
limiter.

Webasto Thermo 90 Specifications

General

Brand	Webasto
Model	Thermo 90
Category	Water Heater
Language	English