115Vac Circuit Trace - Bradford White TTW 75 SERIES Service Manual

120 VAC Circuit Trace
Step 1. Verify 120VAC 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
None, Control LED not
on or flashing.
Disconnect cord set as
shown in photo 28
Using a volt meter set
to volts AC, is there
N
120VAC across
terminals shown in
photo 29 ?
Y
Is there 120VAC
Y
across terminals
shown in photo 30 ?
N
Incorrect supply
voltage polarity
Locate black & white wires at
connector, It may be necessary to pull
back wire sheath to identify wire colors.
(see photo 32)
Is there 120VAC
across black & white Y
wires as shown in
photo 32?
N
Call for technical
support.
making voltage checks to avoid personal injury.
LED status
Short flash, once every
four seconds.
Waiting for
call for heat.
28
Reconnect cord set
shown in photo 28.
Disconnect wire harness
from gas control
(see photo 31).
Replace gas
control.
TTW SERVICE PROCEDURE IX
120 VAC Trace
WARNING
120 volt potential exposure. Use caution
LED status
"Heartbeat", alternates
bright/dim.
Thermostat calling
for heat
29
Check for damage to Y
AC supply power cord.
N
Replace Blower
Wire harness
32
Wire sheath pulled back to
identify wire colors
Check for 120VAC between black & white wires.
-NOTE-
Electronic meter probes required. Use care not to
damage connector during this check.
LED status
Various flashing error
codes.
Verify error code as
listed on page 12
30
Repair damage
31
Page 29
29