Lennox 80MGF Series Manual page 38

NORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
TURN INDUCER ON FOR 1 SECOND.
IS POLARITY REVERSED?
SIGNAL IMPROPER
GROUND AT LED.
NO
SIGNAL HOLDS
UNTIL UNIT IS
PROPERLY
GROUNDED.
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
CHECK FOR MAIN BURNER FLAME SENSE.
IS MAIN BURNER FLAME OFF?
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 0-SECOND DELAY. ACB COOL
SPEED AND ACC. TERMINAL IS ENERGIZED.
THERMOSTAT OPENS.
SYSTEM FAN AND ACC. TERM. OFF
WITH 0-SECOND DELAY.
SURELIGHT CONTROL
COOLING SEQUENCE OF OPERATION
POWER ON
YES
NO
IS THERE YES
PROPER GROUND?
YES
COMPRESSOR OFF.
ABNORMAL COOLING MODE
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
YES
SIGNAL POLARITY REVERSED AT LED.
NO
IS VOLTAGE
ABOVE 75 VOLTS?
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.
Page 38
LOW VOLTAGE SIGNAL AT LET HOLDS
UNTIL VOLTAGE RISES ABOVE 75 VOLTS.