Bradford White UCG100H399, Service Manual

Page: 28 / 48

2 8
S er vi c e P ro c e d u re V:
B l o w er T e st i n g an d R e p l ac e m e nt
Y
D oes b l ower energize ?
Ensure contro l disp l ay
shows “Heating . ” Raise
temperature setpoint if
necessary .
I s co ll ector high l imit
switch in norma ll y c l osed
position ?
Refer to ignition
modu l e/contro l board
i ll ustration . I s there
2 4 VAC between b l ue
and ye ll ow wires at
l ocation J 8 .
Rep l ace ignition
modu l e/contro l board .
I s there 120VAC across
the white and b l ack
wires at the incoming
power harness
connection (see photo
at right) ?
Determine
power
source
prob
l em
and
correct
Check amp draw
through BLACK wire
l ead of b l ower motor . I s
there . 6 to 3 . 0 amps ?
I s b l ower whee l
secured to b l ower
motor shaft ?
Ca ll for
technica l
support .
Rep l ace b l ower . (See
“B l ower Rep l acement
Procedure” . )
Refer to ignition
modu l e/contro l board
i ll ustration . I s there 2 4 VAC
between b l ue and ye ll ow
wires at l ocation J 8 ?
I s co ll ector high l imit
switch in norma ll y
c l osed position ?
Correct safety circuit
prob l em per safety
circuit trace . (See
B l ocked Vent Pressure
Switch T esting” . )
Rep l ace ignition
modu l e/contro l
board .
I s there 120VAC
across white and
b l ack wires at the
b l ower ? (See
photo at right . )
Repair/rep l ace wire
harness .
Rep l ace b l ower . (See
“B l ower Rep l acement
Procedure” . )
Y
Y
Y
Y
Y
N
N
N
N
N
N
Y
Y
N
N
N
Y
120 VAC
power
connection
B l ack wire
l eading to
b l ower l ooped
through amp
probe
120 VAC check
at b l ower
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