Worcester CDi Combi N.G Service Booklet page 39

d6
and fault indicator LED are flashing. (Boiler not available for demands)
Tank overheat thermostat defective
Check
1. B Power OFF the appliance.
B Disconnect the boiler mains
connection.
Check if thermostat is connected
on PCB via ST9
2. B Disconnect lead on thermostat.
Measure the thermostat for
continuity.
Is there continuity?
3. B unplug connector ST9.
Test harness for continuity.
Is there continuity?
4. The PCB control board is damaged.
Tab. 22 d6 Error codes
8 716 115 748 (2009/09)
Supplied By www.heating spares.co Tel. 0161 620 6677
Action
yes go to 2
no B Ensure that ST9 is plugged onto the PCB.
B Reconnect the boiler electrical mains.
B Power ON the appliance
d6? go to 4
yes B Reconnect lead on thermostat.
go to 3
no B Change thermostat.
B Reconnect lead on thermostat.
B Reconnect the boiler electrical mains
connection.
B Power ON the appliance
d6? go to 4
yes d6? go to 4
no B Change or fix wiring to thermostat.
B Reconnect the boiler electrical mains
connection.
B Power ON the appliance.
d6? go to 4
B Reconnect the boiler electrical mains
connection.
B Power ON the appliance.
B Make a note of the altered service function
settings.
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change the control board PCB.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
B Restore service settings previously noted.
RECTIFYING FAULTS
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