Lennox G50UHi Unit Information page 26

NORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
TURN INDUCER ON FOR 1 SECOND (Control board 97L48)
IS POLARITY REVERSED?
LED#1 AND LED#2
ALTERNATING FAST
NO
FLASH. SIGNAL
HOLDS UNTIL UNIT IS
PROPERLY GROUND.
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED AFTER DELAY. COOL SPEED AND
ELECTRONIC AIR CLEANER TERMINAL IS ENERGIZED.
(Control board 69M15, 2-second delay.
Control board 97L48 no delay).
COOLING SPEED AND ELECTRONIC AIR CLEANER
TERMINAL OFF WITH FIELD ADJUSTABLE DELAY
(Control board 69M15, 2 or 45 second delay.
Control board 97L48 no delay).
SURELIGHT CONTROL
COOLING SEQUENCE OF OPERATION
POWER ON
YES
NO
IS THERE
YES
PROPER GROUND? ABOVE 75 VOLTS?
YES
YES
THERMOSTAT OPENS.
COMPRESSOR OFF.
ABNORMAL COOLING MODE
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
YES
LED#1 FAST FLASH LED#2 SLOW FLASH
LED#1 AND LED#2 ALTERNATING FAST
NO
IS VOLTAGE
FLASH. SIGNAL HOLDS UNTIL VOLTAGE
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
Page 26
RISES ABOVE 75 VOLTS.
THERMOSTAT OFF