17.0 Fault Finding
57
© Baxi Heating UK Ltd 2014
FAN LOCKOUT
Rectify wiring.
NO
YES
Unplug
3-way PCB connector
& unplug fan. Is there
continuity from N to O &
from P to Q ?
NO
Unplug
the smaller of the
6-way PCB connector. Is there
continuity from R to S & from T
to U & from
V to W ?
Replace fan.
Rectify wiring.
YES
N
P
R
V
T
Q
O
U
Viewed from
Wire Entry end
S
W
Fan
Connection
PCB
Connection
Fan
Connection
PCB
Connection
NOTE: The fan is supplied with 325 Vdc.
Fan Fault Finding should only be carried out after the
boiler has been electrically isolated.
Lights
Flash Flash On
ON
THERMISTOR
Replace thermistor.
Wiring from PCB to
thermistor faulty.
YES
NO
NO
YES
Replace PCB.
Unplug
thermistor,
Is thermistor resistance between
0.5k
Ω
& 20k
Ω
?
Plug in
thermistor, leave
8-way connector unplugged.
Is resistance at D between
0.5k
Ω
& 20k
Ω
?
D
Viewed from
Wire Entry end
Lights
On Flash On
ON