Bosch CONDENS 5000W - Opening Service Valves; Control Panel and Display

62 | Fault finding and diagnosis AU/NZ
6 720 646 195a (2010/11)
Slow flash
(mostly
off,
flashes
on)
Flashing
(reset
required)
Ignition lockout B Gas present and at correct pressure?
B Gas valve
– Check that there is 35V d.c. to each solenoid
– Check the resistance of each solenoid:
Top solenoid = 380 Ω ± 10% (342 - 418 Ω)
Bottom solenoid = 190 Ω ± 10% (171 - 209 Ω)
B Combustion CO
2
level.
B Flue condition.
– Blocked flue?
B Blocked condensate pipe or frozen condensate.
B Gas valve adjustment.
B Ignition electrodes/harness/connections.
– Check for condition and continuity
B Otherwise replace control board
Slow flash
(mostly
on,
flashes
off)
Flashing
(reset
required)
Flue overheat B Heat exchanger baffles removed and not refitted.
Fast flash Off Volatile lockout
-
Fan does not
run
B Temperature sensors
– Check condition and continuity of leads/sensors
B Fan
– 230V a.c. across the live (purple) and neutral (brown)
B Fan lead
– Check continuity
B Code plug
– Is code plug missing or not inserted properly.
2 pulses No light Not a fault code Service mode selected to minimum, press service button to
return to normal
5 pulses No light Not a fault code Service mode selected to maximum, press service button to
return to normal
Blue light
indication
Lockout
reset button
Fault Possible solution/check
Tab. 28