Webasto Air Top Evo 3900 Workshop Manual - page 46
9 Repair
Air Top Evo 3900/5500
904
9.2.3 Change the control unit
9.2.3.1 Removal
1. Remove the heater (see 8.7.1.1).
2. Remove the casing parts (see 9.2.1).
3. Disconnect the plug connections on the control unit (3,
Fig. 902).
4. Remove the screws (4).
5. Slide the control unit (3) towards the hot air blower and
remove it upwards.
6. Complete the work on stripped down components
(see 9.1.1).
NOTE
Do not carry out any repair work to the control unit.
9.2.3.2 Installation
1. Insert the control unit (3, fig. 902) on the combustion
and hot air blower (1), push it towards the blower
casing and secure it with screws (4).
2. Tighten the screws (4) to 3.0 ± 0.3 Nm.
3. Connect the plug connections on the control unit as
shown in fig. 701.
4. Fit the casing parts (see 9.2.2).
5. Install the heater (see 8.7.1.2)
6. Check the CO
2
setting and adjust it if necessary.
(see 6.2)
9.2.4 Change the overheating sensor
9.2.4.1 Removal
1. Remove the heater (see 8.7.1.1).
2. Remove the casing parts (see 9.2.1).
3. Disconnect plug connection X3 on the control unit
(3, fig. 902).
4. Lever the overheating sensor (9) out of the heat
exchanger’s ribs using a suitable tool (see Detail A).
IMPORTANT
Do not pull the cables.
5. Remove the overheating sensor (9).
9.2.4.2 Installation
1. Measure the resistance of the overheating sensor (9,
fig. 902) (see 6.3.2).
2. Position the overheating sensor (9) and press it into
place by hand.
3. Ensure that the overheating sensor is correctly
positioned in the heat exchanger (7).
4. Connect plug connection X3 to the control unit (3).
5. Fit the casing parts (see 9.2.2).
6. Install the heater (see 8.7.1.2)
9.2.5 Change the combustion and hot air
blower (drive unit)
IMPORTANT
Replace the drive unit (1, fig. 902) only with a drive unit
with the same rating data and the same Part No.
NOTE
The drive unit (combustion and hot air blower) can only be
replaced in full. It cannot be repaired.
9.2.5.1 Removal
1. Remove the heater (see 8.7.1.1).
2. Remove the casing parts (see 9.2.1).
3. Remove the control unit (see 9.2.3.1).
4. Remove the screws (2).
5. Remove the combustion and hot air blower (1)
forwards.
6. Remove and discard the flat seal (6).
7. Complete the work on stripped down components
(see 9.1.1).
9.2.5.2 Installation
1. Ensure that the sealing surfaces on the combustion
and hot air blower (1, fig. 902) and on the heat
exchanger (7) are not damaged.
2. Fit a new flat seal (6) on the flange of the combustion
and hot air blower (1).
3. Position the combustion and hot air blower (1) into the
assembly position and secure it with screws (2).
4. Tighten the screws to 6.0 ± 0.6 Nm..
5. Fit the control unit (see 9.2.3.2).
6. Fit the casing parts (see 9.2.2).
7. Install the heater (see 8.7.1.2)
8. Check the CO
2
setting and adjust it if necessary.
(see 6.2)