Bradford White EF120T4003NA3 Service Manual page 13

CAUTION
Use caution to NOT damage connectors when
making voltage measurements or jumping terminals.
Continued from
previous page.
Y
N
N
Does combustion
blower operate?
Measure voltage
Y
between yellow (J-2)
and ground. Is there
Y
17-30 VDC?
Replace blower.
Y
Can sparking be
seen/heard at the spark
rod and ground rod?
Y
Y
Does main burner light?
Y
Y
Does burner continue until
thermostat set point is
reached? See setting
display in Service Mode
and displaying
temperature sensors.
Y
Does blower post-purge for
Y
30 seconds?
Y
System O.K.
Y
Troubleshooting
Error code 62 on display. Measure voltage
between black and white wires, of the 3
wire harness, at the blower (make sure the
digital display shows "heating" in the status
mode, if not increase the setpoint). Is there
110-120 VAC?
Check that the 5 wire blower
Y
modulation harness is plugged
in to the blower.
Y
N
Y
Replace control board.
N
Remove high voltage wire connected at
N
the spark rod and hold approximately 1/4"
from metal ground with insulated pliers
N
during the ignition cycle (3 second spark
trial period). Is there spark to ground?
Error code 110 on display.
N
See main burner lights, no
flame signal in section
Combustion System Testing
and Replacement (pg 23).
N
See Combustion System Testing
and Replacement (pg 23).
N
Check to see if digital
display shows any other
error codes (67–pressure
switch, 67–vent safety
switch, or 80–high limit).
If so, refer to the
appropriate section(s) for
testing and replacement.
120 volt potential exposure. Use caution making
voltage checks to avoid personal injury.
N
N
Y
Y
N
N
Y
Y
Check continuity of spark rod and spark
rod gap to burner (see Spark Rod Gap
Adjustment, pg 37).
120T Control Board Schematic
13
WARNING
Verify 120V from power switch. Replace
power cord/blower harness if digital
display shows "heating" and no voltage
is present to the blower.
Plug in the wire harness (If this
N
N harness is unplugged blower will
run constantly).
Check resistance of high voltage
cable. Resistance should be 0-1
ohms. If resistance is high, replace
spark cable. If spark cable is good,
replace control board.
N
13