Change The Control Unit - Webasto Air Top Evo 3900 Workshop Manual

9 Repair

9.2.3 Change the control unit

9.2.3.1 Removal
1. Remove heater (see 8.7.1.1).
2. Remove casing parts (see 9.2.1).
3. Disconnect plug connections on control unit (3, Fig.
903).
4. Remove screws (4).
5. Slide the control unit (3) towards the hot air fan and re-
move it upward.
6. Complete the work on stripped down components
(see 9.1.1).
Do not carry out any repair work to the control unit.
9.2.3.2 Installation
1. Insert control unit (3, Fig. 903) on combustion and hot
air fan (1), slide toward fan housing and fasten with
screws (4).
2. Tighten the screws (4) to 3.0 ± 0.3 Nm.
3. Insert plug connections on control unit as shown in Fig.
701.
4. Mount casing parts (see 9.2.2).
5. Install heater (see 8.7.1.2)
6. Check the CO setting and adjust it if necessary.
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(see 6.3)
9.2.4 Change the overheating sensor
9.2.4.1 Removal
1. Remove heater (see 8.7.1.1).
2. Remove casing parts (see 9.2.1).
3. Disconnect plug connection X3 from control unit
(3, Fig. 903).
4. Lever overheating sensor (8) out of heat exchanger's
ribs using a suitable tool (see Detail A).
IMPORTANT
Do not pull the cables.
5. Remove overheating sensor (8).
9.2.4.2 Installation
1. Conduct resistance measurement on overheating sen-
sor (8, Fig. 903) (see 6.4.5).
2. Position overheating sensor (8) and press it into place by
hand.
3. Ensure that overheating sensor is correctly positioned in
heat exchanger (7).
4. Connect plug connection X3 to the control unit (3).
5. Mount casing parts (see 9.2.2).
6. Install heater (see 8.7.1.2)
904
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NOTE
9.2.5 Change combustion and hot air fan
(drive unit)
Only replace the drive unit (1, Fig. 903) with a drive unit with
the same rating data and the same ID No.
The drive unit (combustion and hot air fan) can only be com-
pletely replaced. It cannot be repaired.
9.2.5.1 Removal
1. Remove heater (see 8.7.1.1).
2. Remove casing parts (see 9.2.1).
3. Remove control unit (see 9.2.3.1).
4. Remove screws (2).
5. Remove the combustion and hot air fan (1) toward
front.
6. Remove and discard flat seal (6).
7. Complete work on stripped down components
(see 9.1.1).
9.2.5.2 Installation
1. Make sure that sealing surfaces on combustion and hot
air fan (1, Fig. 903) and heat exchanger (7) are not dam-
aged.
2. Fit a new flat seal (6) on the flange of the combustion
and hot air fan (1).
3. Move combustion and hot air fan (1) into assembled po-
sition and fasten with screws (2).
4. Tighten screws to 6.0 ± 0.6 Nm..
5. Install control unit (see 9.2.3.2).
6. Mount casing parts (see 9.2.2).
7. Install heater (see 8.7.1.2)
8. Check the CO
(see 6.3)
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Air Top Evo 3900/5500
IMPORTANT
NOTE
setting and adjust it if necessary.
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