14.0 FAULT FINDING
42
Publication No. 5106451
Fill system and
switch pump on.
Replace control PCB.
Replace flow switch.
Remove blockage.
Is there
water in system
and pump on ?
Is
flow switch short
circuit
(G)
?
Is
flow switch
blocked ?
Dry-fire Lockout
NO
NO
NO
YES
NO
YES
Replace thermistor.
Is
thermistor short
circuit ?
YES
No Fan Run
YES
NO
Is
thermistor between
0.5k
Ω
and 20k
Ω
?
Replace flow
temperature
thermistor (red)
Replace control PCB.
YES