Webasto Thermo Pro 90 Workshop Manual - Thermo Pro 90
Thermo Pro 90
9 Maintaining and Replacing Components
908
9.10 Replacing heat exchanger
Removal
1. Remove heater (see Section 8.5.1).
2. Remove circulation pump (see Section 9.4).
3. Remove overheating protection (see Section 9.5).
4. Remove coolant temperature sensor (see Section 9.6).
5. Remove burner head with combustion air fan (see Sec-
tion 9.9).
6. Carry out measures on components when dismantled
(see Section 9.2), check for damage (cracks, deforma-
tion, etc.) and replace if necessary.
Clean soot off inner jacket of heat exchanger.
Installation
1. Install burner head with combustion air fan (see Section
9.9).
2. Install coolant temperature sensor (see Section 9.6).
3. Install overheating protection (see Section 9.5).
4. Mount circulation pump (see Section 9.4).
5. Install heater (see Section 8.5.2).
9.11 Replacing control unit
Removal
1. Disconnect electrical connections (see Section 9.3).
2. Unlock control unit and pull off of combustion air fan
cap.
Installation
1. Slide control unit onto combustion-air fan cap until
locking bar engages.
2. Insert electrical connection, see cautionary note!
3. Close control unit door until it engages.
IMPORTANT
Always ensure proper handling when producing the electri-
cal connection of the individual connectors on the control
unit.
This means all connectors are manually pushed as far as pos-
sible into the respective position provided for them in the
control unit. Only then is the control unit door locked.
The control unit door is not an aid for pushing in connec-
tors!
It only locks the connectors against slipping out.
9.12 Replacing exhaust temperature sensor
Removal
1. Disconnect electrical connections (see Section 9.3).
2. Lever cable clip off burner head rib. (sketch position of
clip if necessary).
3. Unscrew screw fitting of hold-down device and pull out
exhaust temperature sensor.
Installation
1. Slide exhaust temperature sensor into burner head.
2. Fix exhaust temperature sensor in place on burner head
with hold-down device and screw. The tightening
torque of the screw fitting of the hold-down device is
2.5 Nm ± 10%.
3. Fix exhaust temperature sensor cable in place on burner
head rib by pressing on clip. When doing so, ensure
torque-free routing of cable between exhaust tempera-
ture sensor and clip.
NOTE
In case of a mechanical defect of the exhaust temperature
sensor due to an external cause, this component can be
replaced without additional work.
However, if an apparent thermal defect has occurred or if
no mechanical defect can be recognised in spite of a fault
message, then additional work is required. This means visual
inspection of the burner unit, exhaust pipes, combustion
pipe and the heat exchanger ribs (inner surface). In the proc-
ess, check for unusual amounts of soot, combustion resi-
dues and carbonisation. Should this be the case, then all
affected parts must be cleaned. Here the burner unit must
also be checked for thermal damage by an expert and
replaced if necessary.
IMPORTANT
The exhaust temperature sensor must be handled carefully
- it is a sensitive electronic ceramic component!
Tensile loading of the exhaust temperature sensor cable on
the sensor head must always be avoided during installation
and heater operation.
Sharp bends in the cable at the sensor head are not permit-
ted in order to prevent damage to the Teflon insulation of
the cable.
Do not pull on the cable after the exhaust temperature sen-
sor is installed!
Should a sensor be dropped during maintenance work, then
a new sensor must be installed.
The proper condition of the mica disc (insulation) on the
sensor, the force-free seating of the cable clips of the
exhaust temperature sensor and the loose routing of the
exhaust temperature sensor cable to the control unit must
be ensured during installation.
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