Service Procedure V: Blower Testing And Replacement - Bradford White EF120T4003N3 Service Manual

Does blower energize?
Ensure digital display
shows "Heating." Raise
temperature setpoint if
necessary.
N
Is there 120VAC across
the white and black
wires at the incoming
power harness
connection? (see image
to right).
Call
Y Y
Technical
Support.
Y Y
Refer to ignition control
board illustration below. Is
there 24-28VAC between
blue and yellow wires at
location J8?
Y Y
Is there 120VAC
N
across white and
black wires at the
blower? (see
image above).
Y
Replace blower (see
Blower Replacement
Procedure, pg 31).
30
Service Procedure V:
Blower Testing and Replacement
Are collector high limit
Y Y
switch and pressure
switches in normally
closed position?
N
Check vent.
Correct safety
circuit.
N
Determine power source
problem and correct.
Is blower wheel
Y Y
secured to blower
motor shaft?
N
Replace blower (see
Blower Replacement
Procedure, pg 31).
Are collector high
N
limit switch and
pressure switches in
normally closed.
Y
Correct safety
Replace ignition
circuit problem per
control board.
safety circuit trace
(see Blocked Vent
Pressure Switch
Testing, pg 33).
Repair/replace
wire harness.
J8 Molex Connector
Refer to ignition
Y
control board
illustration below. Is
there 24-28VAC
between blue and
yellow wires at
location J8?
Y
Check amp draw
through black wire
lead of blower motor.
Is there approximately
1.5 to 5.5 amps?
N
Black wire
leading to
blower looped
through amp
probe
N
30
N
Replace ignition
control board.
120 VAC
power
connection
120 VAC check at
blower
120 Control Board Schematic