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b −If electrode/flame sensor sparks but has 0" voltage at
the valve during tries for ignition, check the wiring be
tween valve and blower/ignition control, check valve
ground.
c −If electrode/flame sensor sparks 24 volts to valve,
flame is established but does not hold in, check
ground between module and burner, make sure that
the electrode/flame sensor is properly located in the
middle of the flame stream, check system ground.
Check to see if electrode/flame sensor is located in the
flame stream properly.
d) If electrode/flame sensor sparks 24 volts to valve but
system fails to ignite, check to make sure that the gas
supply and gas valve are on, check to see if orifice
plugged, and make sure electrode/flame sensor are
properly located.
Furnace lights and flame rollout occurs or burners have
delayed ignition.
a) Make sure that the carryovers on adjoining burners
are screwed fast and are level with respect to one
another.
b) Make sure electrode/flame sensor is properly located.
c) Make sure all air is purged from gas lines.
Main burners light, but exhibit erratic flame characteristics.
Check the main burner orifices for obstruction and align
ment. Removal procedure is described in Burner Instruc
tions." Clean or replace burner orifices and burners as
needed.
LED Codes & Flash Rates
The following blower/ignition control board (DS1) LED
codes will indicate normal or abnormal operations:
Slow Flash
Normal operation, no call for heat
One flash per second
Fast Flash
Normal operation, call for heat
Two flashes per second.
2 Flash
System lockout − failed to detect or sustain flame
Two flashes in one second with a one second pause.
3 Flash
Pressure switch open or closed
Three flashes in one and one−half seconds with a one sec
ond pause.
4 Flash
High limit /or rollout switch open
Four flash in two seconds with a one second pause.
5 Flash
Flame sensed and gas valve not energized
Five flashes in two and one−half seconds with a one second
pause.
Steady
Internal failure (micro−controller failure; self−check)
Repair Parts & Accessories
The following repair parts are available from your local dealer. When ordering parts, include the complete model number
and serial number which are printed on the unit rating plate.
Control Group
Blower Group
Heating Group
Rollout Switch
Blower Housing Assembly
Gas Manifold
Transformer
Blower Wheel
Main Burner Orifices
Limit Control
Blower Motor
Main Burners
Gas Valve
Blower Motor Mount
Heat Exchanger
Blower/Ignition Control
Blower Motor Capacitor (if used)
Cooling Group
Electrode
Combustion Air Inducer
Compressor
Flame Sensor
Fan Blade
Evaporator Coil
Auxiliary Limit
Fan Motor
Drier
Pressure Switch
Fan Motor Capacitor
Cap. Tube or Expansion Valve
Contactor
Capacitor
Condenser Coil
Accessories
Description
Kit Number
LENNOX Cat.
Number
Low Ambient Control
ALOAM111−1
42K88
High Pressure Cut−out Kit
AHPSW436−1
42K89
Timed Off Control
ATIMR446−1
42K90
LP Gas Conversion
ALPKTS533−1
42K91
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