Junkers ZWC 18-3 MFK, Service Manual

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E rror
C ode
category
E rror D escription
C ontrol S tep RSF OF Page
A4 2 Flue gas lesks from flue hood Check flue gas way
?
?
?
?
?
?
?
?
?
?
?
?
A2, C3 2,4 Lesk fromcombustion chamber
Flue gas NTC blocked
Fast temperature
increase detected in CH.
Check system pressure and by pass and
pump
Check primary heat exchanger for any
blockage
X
X
X X
A3 2
2
2
1
4
3
2
3
4
4
Check flue gas temperature NTC and
its connection
X
d4
C1 X
C4, C6 X
E9 X X
A6 X
E2 X X
A8 X X
EA X X
F7 X X
Table. 5 Error Codes
6 Troubleshooting
6.1 How to use Error codes
Each error codes explained with general error reasons. Follow
the instructions to remove the error
6.2 Failure display
The failures are divided into 4 groups:
? Category 1:appliance remains locked until on/off switch is
pressed.
?
Category 2: appliance remains locked until error is removed
?
Category 3: appliance goes on limited working
?
Category4: appliance remains locked until reset button is
pressed
E rror
Air pressure switch opens
during operation Check air pressure switch connecting
pipes flue gas way and fan
Check air pressure switch connecting
pipes flue gas way and fan
Air pressure switch not
opening or closing
Over heat thermostat
triggered.
Combustion chamber NTC is
defective
CH flow NTC is defective
BUS communication
interrupted
Flame not detected
Flame sensed after
appliance switched off
Check system pressure, temperature
limiter, pump, fuse 3 on HT3.
Check combustion chamber
NTC and its connections
Check CH flow NTC and its
connections
Check connection cable and / or
controller
Check gas inlet valve if it is open.
Check gas inlet pressure, ignition
electrode and cables
Check ionization electrode and its
cables. Check wetness on pcB
6 720 660 238 (2008/07)
29
| 29 Troubleshooting