Lennox 80MGF Series Manual page 27

NORMAL HEATING MODE
LED: SLOW FLASH RATE
THERMOSTAT CALLS FOR HEAT
LED: FAST FLASH RATE
FLAME OFF?
YES
CONTROL SELF−CHECK OKAY?
YES
HI LIMIT SWITCH CLOSED?
YES
PRESSURE SWITCH OPEN?
YES
COMBUSTION AIR BLOWER ON?
PRESSURE SWITCH CLOSED?
YES
PREPURGE (45 seconds)
IGNITION TRIAL (7 seconds) −− START IGNITION
SPARK, OPEN MAIN GAS VALVE. INCREMENT
TRIAL REGISTER. HAS FLAME BEEN
REGISTERED WITHIN 7 SECONDS?
YES
SYSTEM FAN ON.
(Fixed 45−second delay)
FLAME SENSE OKAY?
YES
FLAME CONTINUOUSLY CHECKED?
ROLLOUT SWITCHES CLOSED
YES
HI LIMIT SWITCH CLOSED?
YES
PRESSURE SWITCH CLOSED?
YES
THERMOSTAT OPENS
LED: SLOW FLASH RATE
COMB. AIR BLOWER OFF (5 sec. delay)
FAN OFF (After selected 90, 120,
180, or 240 delay)?
80MGF TROUBLESHOOTING SEQUENCE
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
Page 27
ABNORMAL HEATING MODE
LOCKOUT: MAIN VALVE OFF
COMB. AIR AND SYSTEM FANS ON
RESET THERMOSTAT
LED: 5 flash if flame sensed with valve off
LED: Steady on if control board failure
CHECK TO SEE IF MAIN VALVE IS OFF.
SEQUENCE HOLDS UNTIL HI LIMIT CLOSES.
LED: 4 flashes.
CHECK TO SEE IF MAIN VALVE IS OFF.
SEQUENCE HOLDS UNTIL PRES. SWITCH OPENS.
LED: 3 flashes.
CHECK TO SEE IF MAIN VALVE IS OFF.
SEQUENCE HOLDS UNTIL PRES. SWITCH CLOSES.
LED: Fast flash rate.
MAIN VALVE AND SPARK ARE OFF.
INCREMENT TRIAL REGISTER
THREE TRIALS COMPLETED?
IGNITION RESET PERIOD
COMBUSTION & SYSTEM FANS OFF.
IS 60 MIN. RESET PERIOD COMPLETE?
LED: Fast flash rate.
MAIN VALVE AND SPARK OFF.
START IGNITION SPARK (IN 0.8 SEC. MAXIMUM).
HAS FLAME BEEN DETECTED WITHIN 7 SEC.?
YES
SEQUENCE HOLDS. MAIN VALVE OFF.
COMBUSTION AND SYSTEM FANS ON.
RESET OR REPLACE ROLLOUT SWITCH.
LED: 4 flashes.
MAIN VALVE OFF. COMBUSTION & SYSTEM FANS ON.
SEQUENCE HOLDS UNTIL SWITCH CLOSES.
LED: 4 flashes for hi limit.
LED: 3 flashes for pressure switch.
SWITCH CLOSED
COMBUSTION FAN ON. SYSTEM FAN OFF.
(AFTER DELAY TO OFF INTERVAL COMPLETED.)
LED: Fast flash rate.
NO
YES
YES
NO
YES