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WARNING
Shock hazard.
Disconnect power before servicing. Integrated
Control Board is not field repairable. If control is
inoperable, simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
5. Integrated Control Board(A92)
SureLight Board 100869
G6OUH units are equipped with the Lennox two−stage in-
tegrated SureLight control board. The system consists of
a ignition / blower control board (figure 5) with control pin
designations in tables 8 and 9 and and ignitor (figure 8).
The board and ignitor work in combination to ensure fur-
nace ignition and ignitor durability. The SureLight inte-
grated board controls all major furnace operations. The
board features a red LED light, for furnace status and trou-
bleshooting. The LED flashes in X" + Y" codes. For ex-
ample using table 10 under PRESSURE SWITCH
CODES", if the red LED flashes 2 times, then off for 2 sec-
onds then flashes 3 times, the low pressure switch is failed
open. The board also has two 120 volt accessory termi-
nals rated at (1) one amp each and one 24 volt accessory
terminal rated at 0.5.
Electronic Ignition
At the beginning of the heat cycle the SureLight control
monitors the first stage and second stage combustion air
inducer prove switch. The control will not begin the heating
cycle if the first stage prove switch is closed (by−passed).
Likewise the control will not begin the second stage heating
cycle if the second stage prove switch is closed, and will re-
main in first stage heat. However, if the second stage prove
switch closes during the first stage heat pre−purge, the con-
trol will allow second stage heat. Once the first stage prove
switch is determined to be open, the combustion air induc-
er is energized on low (first stage) heat speed. When the
differential in the prove switch is great enough, the prove
switch closes and a 15−second pre−purge begins. If the
switch is not proven within 2−1/2 minutes, the control goes
into Watchguard−Pressure Switch mode for a 5−minute re−
set period.
After the 15−second pre−purge period, the SureLight ignitor
warms up for 20 seconds after which the gas valve opens
for a 4−second trial for ignition. The ignitor energizes during
the trial until flame is sensed. If ignition is not proved during
the 4−second period, the control will try four more times with
an inter purge and warm−up time between trials of 35 sec-
onds. After a total of five trials for ignition (including the ini-
tial trial), the control goes into Watchguard−Flame Failure
mode. After a 60−minute reset period, the control will begin
the ignition sequence again.
NOTE − Board 100869 DOES NOT ramp down voltage
to the ignitor. A regulated 95 volts is provided to the ig-
niter at ignition.
Two Stage Operation / Thermostat Selection Jumper
The control can be utilized in two modes: SINGLE−STAGE
thermostat or TWO−STAGE thermostat. The thermostat
selection is made using a dip switch (figure 4) and must be
positioned for the particular application. The dip switch is
factory set on TWO" for use with a two−stage thermostat
with two stage heat. Re−position dip switch to SINGLE" for
use with a single stage thermostat with two stage heat.
While in the single−stage thermostat mode (single dip
switch setting), the burners will always fire on first−stage
heat. The combustion air inducer will operate on low speed
and indoor blower will operate on low heat speed. After a
10 minute recognition period, the unit will switch to second
stage heat. While in the two−stage thermostat mode (two
dip switch setting) the burners will fire on first−stage heat.
The combustion air inducer will operate on low speed and
indoor blower will operate on low heat speed. The unit will
switch to second−stage heat on call from the indoor thermo-
stat. If there is a simultaneous call for first and second stage
heat, the unit will fire an first stage heat and switch to sec-
ond stage heat after 30 seconds of operation. See Se-
quence of Operation flow charts in the back of this manual
for more detail.
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