Bradford White U-TW4-75S-76R-3N - Manual (Page 32)

U TTW SERVICE PROCEDURE XI
115 VAC Trace
WARNING
115 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
Disconnect cord set as
shown in photo 27.
LED status
None, Control LED not
on or flashing.
Step 1. Verify 115VAC and proper polarity at wall outlet.
Step 2. With unit plugged in and control power switch in the “ON” position verify LED status.
LED status
Short flash, once every
four seconds.
LED status
“Heartbeat”, alternates
bright/dim.
LED status
Various flashing error
codes.
Waiting for
call for heat.
Thermostat calling
for heat
Verify error code as
listed on page 12
Using a volt meter set to
volts AC, is there 115VAC
across terminals shown
in photo 28?
N
Y
27 28
Reconnect cord set
shown in photo 27.
Repair damage
Check for damage to AC
supply power cord.
Y
N
Replace Blower
31
Check for 115VAC between black & white wires.
-NOTE-
Electronic meter probes required. Use care not to
damage connector during this check.
Wire sheath pulled back to
identify wire colors
30
Wire harness
Disconnect wire harness
from gas control
(see photo 30).
Locate black & white wires at connector, It
may be necessary to pull back wire sheath
to identify wire colors
(see photo 31).
Y
N
Replace gas
control.
Is there 115VAC across
black & white wires as
shown in photo 31?
Call for technical
support.
Is there 115VAC across
terminals shown in
photo 29?
N
Y
Incorrect supply
voltage polarity
29
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115 VAC Circuit Trace
R
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