Troubleshooting - Lennox EL280UH Installation Instructions Manual

Troubleshooting: Heating Sequence of Operation
POWER ON
CONTROL SELF−CHECK OKAY?
POLARITY OKAY?
YES
PROPER GROUND?
YES
NORMAL OPERATION:
STATUS LED −− PULSE
NO
THERMOSTAT CALLS FOR HEAT:
STATUS LED −− HEARTBEAT
YES
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
YES
ROLLOUT SWITCH CLOSED?
YES
FIRST (LOW) STAGE PRESSURE SWITCH
CONTACTS OPEN?
YES
SECOND (HIGH) STAGE PRESSURE SWITCH
CONTACTS OPEN?
YES
TWO−STAGE OR SINGLE−STAGE THERMOSTAT
CALL FOR HEAT
COMBUSTION AIR INDUCER ON LOW SPEED.
1
STATUS LED −− HEARTBEAT
CONTINUED ON NEXT PAGE
If the furnace is operating on continuous fan mode (terminals R" and G" are energized), the combustion
1
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.
HEATING SEQUENCE OF OPERATION
NORMAL AND ABNORMAL HEATING MODE
IS THERE A
A
B
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
INDOOR BLOWER OFF. (RESET CONTROL BY
TURNING MAIN POWER OFF.)
NO
POLARITY REVERSED.
STATUS ERROR CODE 5 + 4.
NO
SIGNAL HOLDS UNTIL UNIT IS PROPERLY GROUNDED.
STATUS ERROR CODE 5 + 3.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER ON. HAS PRIMARY OR
SECONDARY LIMIT RESET WITHIN 3 MINUTES?
STATUS ERROR CODE 3 + 1.
NO
60−MINUTE LIMIT WATCHGUARD MODE.
GAS VALVE OFF, COMBUSTION AIR INDUCER
OFF, INDOOR BLOWER OFF WITH DELAY.
STATUS ERROR CODE 4 + 5.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
NO
INDOOR BLOWER ON.
STATUS ERROR CODE 5 + 1.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS
RESET AND MAIN POWER IS INTERRUPTED OR
NO
T'STAT IS CYCLED OFF/ON FOR 3 SEC. MINIMUM.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF. CONTROL REMAINS UNTIL
PRESSURE SWITCH IS DETECTED OPEN.
STATUS ERROR CODE 2 + 4
NO
GAS VALVE OFF.
COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF.
CONTROL WILL NOT ATTEMPT SECOND−STAGE
OPERATION DURING THIS HEAT DEMAND.
FIRST−STAGE OPERATION WILL BE ATTEMPTED.
STATUS ERROR CODE 2 + 6.
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NO
YES
NO
YES