Lennox G51MP SERIES Installation Instructions Manual page 51

®
SureLight Troubleshooting: Cooling Sequence of Operation
NORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
IS POLARITY REVERSED?
ROLLOUT SWITCHES MONITORED CONTINUOUSLY.
ARE ROLLOUT SWITCHES CLOSED?
DS1 & DS2: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 2-SECOND DELAY. COOL
SPEED TERMINAL IS ENERGIZED. EAC
TERMINAL IS ENERGIZED.
SYSTEM FAN AND EAC TERM. OFF
WITH 2− OR 45-SECOND DELAY.
SURELIGHT CONTROL
COOLING SEQUENCE OF OPERATION
POWER ON.
YES
NO
NO
IS VOLTAGE
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 DS1 & DS2.
INTERRUPT MAIN POWER TO RESET CONTROL.
YES
DS1 FAST FLASH DS2 SLOW FLASH.
DS1 AND DS2 ALTERNATING FAST
FLASH. SIGNAL HOLDS UNTIL VOLTAGE
RISES ABOVE 75 VOLTS.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT DS1 & DS2.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
Page 51