40
2. HEATING DOESN’T WORK BUT HOT WATER WORKS.
Is the central heating service and
temperature selector in the on
position?
IN
Are the time clock and (room
thermostat if fitted) calling for
heat? (Contacts closed) Check for
13 v dc at J4 on PCB, (black/black
left hand pair).
Are the wiring and connections from
the front panel control PCB to the
main PCB o.k.?
Turn on the heating
selector to the maximum
position.
Check for correct operation
of the clock/room
thermostat and the wiring
and connections of the
above, rectify or replace
clock or thermostat as
necessary.
Remake the connections from
the front panel control PCB to
the main PCB.
Replace the front panel
control PCB.
Replace the main PCB.
No
No
No
No
Yes
Yes
Yes
OUT
Are the values of the front panel
control PCB variable resistors
correct?
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