Lennox G32V Series Service Literature page 23

Once the prove switch (first stage prove switch for
G32V−75) is determined to be open, the combustion air in-
ducer 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−min-
ute 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 be-
tween trials of 35 seconds. After a total of five trials for igni-
tion (including the initial trial), the control goes into Watch-
guard−Flame Failure mode. After a 60−minute reset period,
the control will begin the ignition sequence again.
The SureLight control board has an added feature that pro-
longs the life of the ignitor. After a successful ignition, the
SureLight control utilizes less power to energize the ignitor
on successive calls for heat. The control continues to ramp
down the voltage to the ignitor until it finds the lowest
amount of power that will provide a successful ignition. This
amount of power is used for 255 cycles. On the 256th call
for heat, the control will again ramp down until the lowest
power is determined and the cycle begins again.
Two Stage Operation / Thermostat Selection Jumper
The control can be utilized in two modes: SINGLE−STAGE
thermostat or TWO−STAGE thermostat. The thermostat
selection jumper E20, located just below dip switches 1
through 3 (figure 16), must be positioned for the particular
application. The jumper is factory set on TWO" for use with
a two−stage thermostat with two stage heat. Re−position
jumper to SINGLE" for use with a single stage thermostat
with two stage heat.
While in the single−stage thermostat mode (single jumper
setting), the burners will always fire on first−stage heat. The
combustion air inducer will operate on low speed and in-
door blower will operate on low heat speed. After a 10 min-
ute recognition period, the unit will switch to second stage
heat. While in the two−stage thermostat mode (two jumper
setting) the burners will fire on first−stage heat. The com-
bustion 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 thermostat. If
there is a simultaneous call for first and second stage heat,
the unit will fire an first stage heat and switch to second
stage heat after 30 seconds of operation. See Sequence of
Operation flow charts in the back of this manual for more
detail.
TW0−STAGE, VARIABLE SPEED INTEGRATED
LEDs
ON−BOARD
JUMPER W914
(cut when CCB1 or
Harmony II are used)
THERMOSTAT CONNECTIONS (TB1)
DIP SWITCH FUNCTIONS
DIP SWITCH(ES)
1 and 2
3
4
5 and 6
7 and 8
9 and 10
11 and 12
Page 23
CONTROL BOARD
ON−BOARD
JUMPER W951
ON−BOARD
(cut when heat pump is
JUMPER W915
used with FM21)
(cut when two−stage
cooling is used)
FUNCTION
Blower Off Delay
Second Stage ON Delay (Single−stage t'stat)
Not used
Cooling Mode Blower Speed
Blower Speed Adjustment
Cooling Mode Blower Ramping Profile
Heating Mode Blower Speed
FIGURE 16
DIAGNOSTIC
LEDs
DIP
SWITCHES
1 − 3
DIP
SWITCHES
5 − 12
LED