Page 58
Troubleshooting: Heating Sequence of Operation (Continued)
HEATING SEQUENCE OF OPERATION
FIRST−STAGE (LOW FIRE) PRESSURE
SWITCH CLOSED WITHIN 2.5 MINUTES?
GAS VALVE OFF. COMBUSTION AIR INDUCER
OFF. INDOOR BLOWER OFF. UNIT WILL RETRY
AFTER 5−MINUTE WAIT PERIOD.
STATUS ERROR CODE 2 + 3.
YES
NO
15−SECOND COMBUSTION AIR INDUCER
PRE−PURGE INITIATED BY CLOSED FIRST−STAGE
PRESSURE SWITCH (or 15 SECOND
INTER−PURGE PERIOD.)
STATUS LED −− HEARTBEAT.
IGNITOR WARM−UP (20 SECONDS)
STATUS LED −− HEARTBEAT.
IS VOLTAGE ABOVE 90 VOLTS?
NO
COMBUSTION AIR INDUCER OFF, IGNITER OFF.
SIGNAL HOLDS UNTIL VOLTAGE RISES ABOVE 95
VOLTS. STATUS ERROR CODE 4 + 8.
YES
NO
COMBUSTION AIR INDUCER OFF, IGNITOR OFF.
SIGNAL HOLDS UNTIL IGNITOR IS REPLACED OR
RECONNECTED.
STATUS ERROR CODE 4 + 7.
YES
AT END OF IGNITOR 20 SECOND WARM UP
PERIOD, 4−SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS, IGNITOR ENERGIZED DURING
4−SECOND TRIAL UNTIL FLAME SENSED.
YES
4−SECOND FLAME STABILIZATION PERIOD.
FLAME RECTIFICATION CURRENT CHECK
CAN FLAME BE PROVEN WITHIN 4
SECONDS AFTER GAS VALVE OPENS?
(u0.20 microamps)
GAS VALVE OFF. COMBUSTION AIR
INDUCER ON. INDOOR BLOWER OFF.
STATUS LED −− HEARTBEAT.
HAS CONTROL FAILED TO SENSE
FLAME FOR FIVE CONSECUTIVE TRIES
DURING A SINGLE HEAT DEMAND?
YES
THERMOSTAT CALLS FOR HEAT
STATUS LED − HEARTBEAT.
(Refer to box A on previous page)
YES
FLAME PRESENT?
NO
HAS CONTROL RESET IGNITION SEQUENCE
FOUR (4) TIMES?
WATCHGUARD MODE.
STATUS ERROR CODE 4 + 3.
YES
CONTINUED ON NEXT PAGE
YES
NO
NO
CONTINUED
IS IGNITOR INTACT AND CONNECTED?
WATCHGUARD MODE. GAS VALVE OFF,
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF.
STATUS ERROR CODE 4 + 1.
IS 60−MINUTE RESET PERIOD COMPLETE?
NO
YES
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