Bradford White UCG100H399, Service Manual

Page: 11 / 48

11
1 2 0 vo l t potentia l exposure . Use caution making vo l tage checks
to avoid persona l injury .
WA R NIN G
Use caution not to damage connectors when making vo l tage
measurements or jumping termina l s
CAUT I O N
Troub l es h oot i ng
System Observat i on for Mode l s w i t h D i rect Spark I gn i t i on
Water Heater F au l t : Water heater does not operate
Disp l ay Error Code : Water heater disp l ay does not
operate - b l ank disp l ay
Check main power supp l y to water heater –
fuse, circuit breaker, p l ug receptac l e, l ine cord or
wiring to water heater .
Check to make sure switch on front of contro l
pane l is in the O N position .
Verify primary vo l tage at the transformer .
Refer to contro l board i ll ustration .
Vo l tage at transformer across b l ack and
white wires shou l d be 110 - 1 2 0 VAC .
Check l ine cord with vo l t meter . Rep l ace
l ine cord if defective .
Verify secondary vo l tage at the contro l board .
Refer to contro l board i ll ustration .
Vo l tage at connector l ocation J8 across
b l ue and ye ll ow wires shou l d be 24 VAC .
I f not, check transformer . Rep l ace
transformer if defective .
Does water heater disp l ay
operate ? I ncrease thermostat
setting if tank is warm .
I s 24 VAC present between
RED and BLACK wire pin
connections on the back of
contro l disp l ay ?
Disp l ay operates - See next page .
Disp l ay operates - See next page .
Rep l ace contro l board .
Check wire
harness for proper
continuity .
Check wires for proper
termination to contro l disp l ay .
Are wire terminations connected
proper l y to contro l disp l ay ?
Rep l ace
contro l
board .
Make proper wire
terminations .
Y
Y
Y
Y
N
N
N
N
Y e ll ow &
B l ue
wires .
B l ack &
White
wires .
11