Bradford White 100T399-SOLA Supplement To Installation & Operation Manual page 13

DIAGNOSTIC ERROR CODES AND TROUBLESHOOTING PROCEDURES FOR 100T399 MODELS WITH
HONEYWELL LOW FIRE START CONTROL SYSTEM
Error Code Definition of Code
No code –
blank display
3-48, 58-60 Internal Faults
49 Voltage too low or high
AC Inputs phase
53
62 Fan speed not proved
67 ILK Off (Interlock Off)
High Limit (Overheat
80
Condition)
93 DHW Sensor Fault
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Cause of Problem and Actions Taken to Correct
Check power supply to the water heater.
Make sure water heater is plugged in and the breaker is on.
Check if there is 120 volts power supply to the LINE connections on the
control board.
If 120 volts is present, check for 24 volts output to SECONDARY
terminals on the Control Board.
Check for loose wires, defective transformer.
Check wire harness connections from display to the control board.
Verify wiring to the wiring diagram.
Check power supply to make sure voltage and frequency is correct.
Check for 24 volts from the transformer to the control board.
Reset module by interrupting power or pressing the reset button on the
module.
Measure the incoming line voltage.
Voltage should be 115-125 volts.
If the voltage is not within this range or there is drastic fluctuation, then
have the incoming power supply checked.
If the line voltage is satisfactory, check the output from the transformer
to make sure it is 22-26 volts.
Replace transformer or wiring if defective.
Check the module and display connections.
Check the module power supply and make sure that frequency, voltage
and VA capacity of the transformer meet specifications.
Check to make sure the wiring connections on the control module from
terminals J4-10 and J8-2 are connected together.
Check the PWM wire harness connection from the blower to the control
module.
Make sure the pin terminals make solid contact.
Measure the resistance of each wire in the wire harness from the
terminal ends.
Replace wire harness if defective.
Check wiring to the normally closed blocked vent pressure switches
and vent limit switch.
Use a voltmeter to find out if either pressure switch or the high limit
switch has opened.
If so, determine the cause (blocked vent terminal, clogged condensate
drain, high temperature in compartment).
If limit switches are closed, check wiring for shorts.
Measure continuity.
If limit switches and wiring check O.K., replace control module.
Check the wiring from the sensor to the control module.
Measure the resistance of each outside wire to the center wire.
If either outside wire has a much different resistance reading, replace
the sensor.
Make sure the sensor is securely held inside the well with the clip.
If the problem persists and the sensor and wiring check O.K., then
replace the control module.
Check the sensor wire harness from the sensor to the control module.
Make sure there are no loose connections to the control plug.
Check the resistance reading from each of the outside wires to the
center (common) wire.
If the ohm readings are not fairly close, replace the sensor.
Replace the control module if the problem persists and the sensor and
wire connections are not defective.
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