Lennox G61MPV Service Manual page 79

CONTINUED
FLAME SIGNAL ABOVE
(w0.23 microamps)
YES
SINGLE−STAGE THERMOSTAT MODE
(E20 SET AT SINGLE")
YES
START SECOND−STAGE RECOGNITION
ON DELAY (10 OR 15 MINUTES).
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
FIRST−STAGE (LOW FIRE)
PRESSURE SWITCH CLOSED?
YES
C
NO
FIRST−STAGE HEAT DEMAND SATISFIED?
DS1 AND DS2 SIMULTANEOUS SLOW FLASH.
YES
GAS VALVE OFF, COMBUSTION AIR INDUCER
OFF FOLLOWING POST PURGE.
INDOOR BLOWER OFF WITH DELAY
DS1 AND DS2 SIMULTANEOUS SLOW FLASH
SECOND−STAGE HEAT DEMAND.
SECOND−STAGE HEAT DEMAND REQUIRED?
DS1 AND DS2 SIMUTANEOUS SLOW FLASH.
YES
SECOND STAGE PRESSURE SWITCH CLOSED?
ABNORMAL FLASH CODE.
NOTE − IF SECOND−STAGE PRESSURE SWITCH
WAS ORIGINALLY FOUND CLOSED,
ABNORMAL CODE WILL FLASH.
NO
SECOND−STAGE 30−SECOND DELAY ON BEGINS.
DS1 AND DS2 SIMULTANEOUS FAST FLASH
YES
SECOND−STRAGE COMBUSTION AIR INDUCER
ON. SECOND−STAGE GAS VALVE ON. HIGH
HEAT INDOOR BLOWER SPEED ON.
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
ON/OFF LED ON.
YES
SECOND−STAGE PRESSURE SWITCH CLOSED
IN LESS THAN TEN (10) SECONDS?
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
YES
CONTINUED ON NEXT PAGE
HEATING SEQUENCE OF OPERATION
NO
YES
TWO STAGE THERMOSTAT MODE
(E20 SET AT TWO")
YES
45−SECOND INDOOR BLOWER ON DELAY BEGINS.
YES
PRIMARY, SECONDARY AND BACKUP SECONDARY
NO
GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,
INDOOR BLOWER ON. DS1 SLOW FLASH, DS2 ON,
(Indoor blower on low speed during 3−minute period)
GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
YES
SECOND−STAGE PRESSURE SWITCH CLOSED
DS1 AND DS2 SIMULTANEOUS SLOW FLASH.
RETURNS TO FIRST−STAGE HEAT MODE WHICH
CONTINUES UNTIL SECOND−STAGE PRESSURE
SWITCH CAN BE PROVEN or HEAT DEMAND IS
NO
INITIATED BEFORE RETRY. WERE 5 ATTEMPTS
Page 79
THERMOSTAT CALLS FOR HEAT.
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
SEE BOX A.
LOW FLAME SIGNAL
(Does not affect control operation)
DS1 SLOW FLASH, DS2 FAST FLASH.
DS1 AND DS2 SIMULTANEOUS FAST FLASH.
YES
LIMITS AND ROLLOUT SWITCHES CLOSED?
NO
ON/OFF LED ON, HEAT LED ON.
HAS PRIMARY, SECONDARY, BACKUP
SECONDARY OR ROLLOUT
SWITCH CLOSED WITHIN 3 MINUTES?
NO
LIMIT SWITCH WATCHGUARD MODE.
INDOOR BLOWER OFF WITH DELAY.
DS1 AND DS2 ALTERNATING SLOW FLASH,
ON/OFF LED OFF, HEAT LED OFF.
IS 60−MINUTE RESET PERIOD COMPLETE?
INDOOR BLOWER OFF AFTER DELAY.
DS1 OFF, DS 2 SLOW FLASH,
ON/OFF LED OFF, HEAT LED ON.
AT BEGINNING OF HEAT DEMAND?
DS1 OFF, DS2 SLOW FLASH,
ON/OFF LED ON, HEAT LED ON.
SECOND STAGE HEAT DEMAND
NO
SATISFIED. FIVE (5) MINUTE WAIT PERIOD
MADE FOR SECOND−STAGE HEAT?
YES
NORMAL OPERATION.
DS1 AND DS2 SIMULTANEOUS SLOW FLASH.
YES
YES
NO