22
12.0 Fault Finding
START
YES
NO
Check mains
supply.
Is there
mains voltage
across terminals
A1 & A2?
YES
NO
Investigate cause
and
rectify fault
Is the
fuse on the
speed select PCB
O.K?
Replace speed
NO
Is there low
voltage between
B1 and B2?
YES
NO
Check external
control wiring.
Reconnect wires
to terminals
B1 & B2.
Replace external
controls
Check
external
control,
rectify or
replace
as
necessary.
NO
Do the
external controls
have/require a mains
supply?
Are both fans
operating?
YES
YES
Replace fuse
Before starting FAULT FINDING
carry out preliminary electrical systems checks
i.e. Earth Continuity, Polarity, Short Circuit
and Resistance to Earth.
Ensure all external controls are operating
and are set to normal running. Ensure that
a mains electrical supply is available to the
unit.
Refer to diagrams below to
identify terminals on components
(e.g. A1, B2 etc).
FINISH
NO
YES
Did this solve
the problem?
NO
YES
Did this solve
the problem?
YES
NO
NO
Clean filter &
heat exchanger
(section 10). Check
duct system and
terminals for
blockages or
damage. Ensure
terminals are
adjusted correctly.
Is there
adequate airflow
at the appliance
inlets and
outlets
Do external
controls switch
the unit to boost?
NO
Correct speed
settings
Is the
boost speed set
higher than the normal
speed on dip
switch C?
NO
YES
Did this solve
the problem?
YES
A2
A1
B2
B1
C
FUSE
SPEED SELECT PCB
YES
Fig. 20
1
2
3
4
5
6
7
8
N
L
1
2
Normal
Boost
1
2
3
4
5
4
5
6
ON
select PCB.