Lennox KGA Series Service Literature page 40

Power:
1- Line voltage from unit disconnect energizes trans­
former T1. T1 provides 24VAC power to terminal strip
TB1. TB1 provides 24VAC to the unit cooling, heating
and blower controls.
Blower Operation:
2- Indoor thermostat terminal G energizes blower contac­
tor K3 with 24VAC. N.O. K3 closes, energizing blower
B3.
Economizer Operation:
3- The economizer control module receives a demand
and energizes exhaust fan relay K65 with 24VAC at
50% outside air damper open (adjustable).
4- N.O. K65-1 and N.O. K65-2 both close, energizing ex­
haust fan motor B10.
1st Stage Cooling (compressor B1)
5- First stage cooling demand Y1 and G are energized by
KGA092/150 Sequence of Operation
Page 40
the thermostat. G energizes blower. 24VAC is routed
through TB1 passing N.C. freezestat S49 and optional
N.C. high pressure switch S4. Compressor contactor
K1 is energized. N.O. contacts K1 close energizing
compressor B1.
6- Optional N.O. low ambient switch S11 closes to ener­
gize condenser fan relay K10. N.O. contacts K10-1 and
K10-2 close energizing condenser fans B4 and B5.
N.C. contacts K10-1 open de-energizing crankcase
heaters HR1 and HR2.
2nd Stage Cooling (compressor B2 is energized)
7- 24VAC is routed through TB1 and proves N.C. freezes­
tat S50 and optional N.C. high pressure switch S7.
Compressor contactor K2 is energized. N.O. K2 con­
tacts close energizing compressor B2.
8- Optional N.O. low ambient switch S84 closes to ener­
gizing condenser fan relay K10. N.O. contacts K10-1
and K10-2 close energizing condenser fans B4 and B5.
N.C. contacts K10-1 open de-energizing crankcase
heaters HR1 and HR2.