g43 service manual - Heating and Air Parts

G43UF Units with Ignition Control Board 78M47 or 100973−01LED#1 = DS1 LED#2 = DS2 See Figure 8HEATING SEQUENCE OF OPERATIONIgnition Control 78M47 / 100973−01NORMAL HEATING MODEABNORMAL HEATING MODEPOWER ONCONTROL SELF−CHECK OKAY?YESIS POLARITY CORRECT?YESIS THERE A PROPER GROUND?YESNONONOGAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER DELAY OFF.LED #1 ONLED #2 ON(RESET CONTROL BY TURNING MAIN POWER OFF.)POLARITY REVERSED.LED #1 −− FAST FLASHLED #2 −− SLOW FLASHIMPROPER GROUND.LED #1 −− ALTERNATING FAST FLASHLED #2 −− ALTERNATING FAST FLASHIS VOLTAGEABOVE 90 VOLTS?NOLED SIGNALS LOW VOLTAGE. CONTROL WILLNOT RESPOND UNTIL VOLTAGE RISES ABOVE90 VOLTS.YESROLLOUT SWITCH CLOSED?YESNOGAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER ON.LED #1 −− ON. LED #2 −− SLOW FLASH.SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSESAND POWER IS RESET OR T’STAT IS INTERRUPTEDFOR MINIMUM OF 1 SECOND.BURNER OFF?(CONTINUOUS FLAME CHECK)YESNOGAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER ON HEATING SPEED.LED #1 −− SLOW FLASHLED #2 −− OFFNONORMAL OPERATION:LED #1 −− SLOW FLASHLED #2 −− SLOW FLASHYESTHERMOSTAT CALLS FOR HEAT:LED #1 −− FAST FLASHLED #2 −− FAST FLASHYESPRIMARY AND SECONDARY LIMIT SWITCH.CLOSED?YESIS COMBUSTION AIRPRESSURE SWITCH OPEN?YESIS COMBUSTION AIR INDUCERENERGIZED?YESHAS COMBUSTION AIR PRESSURESWITCH CLOSED IN 2.5 MINUTES?YESNONONOCOMBUSTION AIR INDUCER OFF.INDOOR BLOWER ONLED #1 SLOW FLASH RATELED #2 −− ONGAS VALVE OFF.COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH DELAY.LED #1 OFFLED #2 SLOW FLASH(Sequence holds until pressure switchopens or thermostat resets control.)PRESSURE SWITCH IS IN WATCHGUARD MODE.GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH DELAY.LED #1 −− OFF. LED #2 −− SLOW FLASH.IS 5-MINUTE RESET PERIOD COMPLETE?YESCONTINUED NEXT PAGEPage 46