Ignition Control Board Diagnostic Codes - Lennox G51MP SERIES Installation Instructions Manual

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SureLight Troubleshooting: Continuous Fan Sequence of Operation
THERMOSTAT CALLS FOR COOLING.
INDOOR BLOWER SWITCHES TO COOL SPEED.
THERMOSTAT OPENS.

Ignition Control Board Diagnostic Codes

DS1
(Red or Green)
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
FAST FLASH
SLOW FLASH
OFF
ALTERNATING
SLOW FLASH
SLOW FLASH
ON
ON
ON
OFF
FAST FLASH
SLOW FLASH
ALTERNATING
FAST FLASH
NOTE − Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).
Drop out flame sense current = 0.15 − 0.24 microAmps.
SURELIGHT CONTROL
CONTINUOUS FAN SEQUENCE OF OPERATION
DS1 & DS2: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT SEQUENCE.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES INDOOR BLOWER AT
FAN SPEED. EAC TERM. IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
NO
YES
INDOOR BLOWER SWITCHES TO SELECTED
BLOWER SPEED. EAC TERM. REMAINS
ENERGIZED.
DIAGNOSTIC CODES
Make sure to Identify LED'S Correctly.
Refer to Installation Instructions for control board layout.
DS2
(Green)
SIMULTANEOUS Power on −− Normal operation.
SLOW FLASH Also signaled during cooling and continuous fan.
SIMULTANEOUS
Normal operation −− Signaled when heating demand initiated at thermostat.
FAST FLASH
Primary or secondary limit switch open. Limit must close within 3 minutes or unit goes into
ON
1−hour Watchguard.
Pressure switch open;
OR: Blocked inlet/exhaust vent;
SLOW FLASH
OR: Condensate line blocked;
OR: Pressure switch closed prior to activation of combustion air inducer.
ALTERNATING Watchguard −− Burners failed to ignite, limit open longer than 3 minutes, or flame sense lost 5
SLOW FLASH times in one heating cycle.
OFF Flame sensed without gas valve energized.
SLOW FLASH Rollout switch open.
ON
Circuit board failure or control wired incorrectly. Check 24−volt and 115−volt connections to
OFF
board.
ON
SLOW FLASH Main power polarity reversed. Switch line and neutral. Improper main ground.
FAST FLASH Low flame signal. Check flame sensor.
The following conditions are sensed during the ignitor warm−up period only:
ALTERNATING 1) Improper main ground;
FAST FLASH 2) Broken ignitor; OR: Open ignitor circuit;
3) Line voltage below 75 volts.
YES
NO
INDOOR BLOWER SWITCHES TO HEAT SPEED
AFTER NORMAL DELAY.
THERMOSTAT OPENS. COMBUSTION AIR INDUCER
AND HUM TERMINALS ARE DE−ENERGIZED
FOLLOWING 5−SECOND POST−PURGE.
INDOOR BLOWER SELECTED TIME OFF DELAY BEGINS.
AFTER DELAY, HEAT SPEED DE−ENERGIZED.
(Blower remains energized during continuous fan mode).
DESCRIPTION
Page 52
HUM (120 VAC & 24VAC)
TERMINALS ENERGIZED
WITH COMB. AIR INDUCER.