Troubleshooting: Heating Sequence of Operation (Continued)
HEATING SEQUENCE OF OPERATION
CONTINUED
THERMOSTAT CALLS FOR HEAT
STATUS LED − HEARTBEAT.
(Refer to box A on previous page)
1FIRST−STAGE (LOW FIRE) PRESSURE SWITCH CLOSED WITHIN 2.0 MINUTES?
YES
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| 15−SECOND COMBUSTION AIR INDUCER | ||
| PRE−PURGE INITIATED BY CLOSED FIRST−STAGE | |||
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| PRESSURE SWITCH (or 15 SECOND | ||
1 | INTER−PURGE PERIOD.) | |||
STATUS LED −− HEARTBEAT. | ||||
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| IGNITOR WARM−UP (20 SECONDS) | ||
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| STATUS LED −− HEARTBEAT. | ||
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| YES |
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| IS IGNITOR INTACT AND CONNECTED? | ||
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| YES |
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NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF. UNIT WILL RETRY AFTER 5−MINUTE WAIT PERIOD.
STATUS ERROR CODE 2 + 3.
COMBUSTION AIR INDUCER |
| LOW AND HIGH | NO | |
| PRESSURE SWITCH |
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ENERGIZED ON HIGH SPEED |
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| CLOSED WITHIN 30 |
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| YES | ||
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COMBUSTION AIR INDUCER OFF, IGNITOR OFF. SIGNAL HOLDS UNTIL IGNITOR IS REPLACED OR RECONNECTED.
STATUS ERROR CODE 4 + 7.
2AT 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.
NO
YES
IS VOLTAGE ABOVE 90 VOLTS?
NO
COMBUSTION AIR INDUCER OFF, IGNITOR OFF. SIGNAL HOLDS UNTIL VOLTAGE RISES ABOVE 95 VOLTS. STATUS ERROR CODE 4 + 8.
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
NO |
FLAME PRESENT?
YES
CONTINUED ON NEXT PAGE
NO
WATCHGUARD MODE. GAS VALVE OFF,
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF.
STATUS ERROR CODE 4 + 1.
IS 60−MINUTE RESET PERIOD COMPLETE?
YES
HAS CONTROL RESET IGNITION SEQUENCE
FOUR (4) TIMES?
WATCHGUARD MODE.
STATUS ERROR CODE 4 + 3.
YES
NO
1If the furnace is operating on continuous fan mode (terminals
air inducer will energize on high speed, the gas valve will energize on second−stage heat and the furnace
will operate on high fire. Furnace will stay on high fire 60 seconds then switch to low fire.
2If combustion air inducer is operating on high speed and gas valve is energized on second− stage heat, 20 seconds after flame is sensed furnace will switch to low fire.
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