Service Manual

50
Troubleshooting
CAUTION
Use caution to NOT damage connectors when
making voltage measurements or jumping terminals.
WARNING
120 volt potential exposure. Use caution making
voltage checks to avoid personal injury.
From previous page.
Does combustion
blower operate?
Refer to control board illustration.
Measure voltage between terminals P7(3)
& P7(5) on the “inducer” output. Make
sure the control displays shows “heating”
in the status mode. If not, increase the
setpoint. Is there 110-120 VAC?
Replace control board if
display shows “heating”
and no voltage is present to
the blower harness. Make
sure there are no error
codes for the temperature
sensors before replacing
control board.
Check the voltage at the
connection to the blower.
Is 110-120 VAC present?
Replace the wire harness.
Replace
blower.
Can sparking be
seen/heard at the spark
rod to the burner?
Remove high voltage wire connected at
the spark rod and hold approximately ¼”
from metal ground with insulated pliers
during the ignition cycle (3 second spark
trial period). Is there spark to ground?
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.
Check continuity of spark rod to burner
(see Spark Rod Replacement, pg 79).
Does the main
burner light?
Error code 62 on display (see main
burner lights, no flame signal in
Combustion System Testing and
Replacement, pg 68).
Does the burner
continue until
thermostat set point is
reached? See setting
display in Service
Mode and displaying
temperature sensors.
Error code 63
on display (see
Combustion
System
Testing and
Replacement,
pg 68).
Does the blower post-
purge for 30 seconds?
System O.K.
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Check to see if control display shows any other error codes (such as 65-high
limit). If so, refer to the appropriate section for testing and replacement.
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