I-Unit Components - Lennox KGA Series Service Literature

I-UNIT COMPONENTS

All 7.5 through 12.5 ton (26.3 through 44 kW) units are con­
figure to order units (CTO). The KGA unit components are
shown in figure 1. All units come standard with removable
unit panels. All L1, L2 and L3 wiring is color-coded; L1 is red,
L2 is yellow and L3 is blue.
A-Control Box Components
KGA control box components are shown in figures 2 and 3.
The control box is located in the upper portion of the com­
pressor compartment.
1-Disconnect Switch S48
(Field-Installed for all units)
All units may be equipped with an optional disconnect switch
S48 or circuit breaker CB10. S48 and CB10 are toggle
switches, which can be used by the service technician to dis­
connect power to the unit.
2-Control Transformer T1 all units
All use a single line voltage to 24VAC transformer in­
stalled in the control box. The transformer supplies pow­
er to control circuits in the unit. The transformer is rated
at 70VA and is protected by a 3.5 amp circuit breaker
(CB8). The 208/230 (Y) voltage transformers use two
208/230V TRANSFORMER
BLUE YELLOW
SECONDARY
208 VOLTS
RED
230 VOLTS
PRIMARY
ORANGE BLACK
FIGURE 4
3-C. A. I. Transformers T3 575V units
All KGA 575 (J) voltage units use transformer T3 located in
the control box. The transformers have an output rating of
0.5A. T3 transformer supplies 230 VAC power to the combus­
tion air inducer motor (B6).
4-Terminal Strip TB1
All indoor thermostat connections are made at terminal
block TB1 located in the control area. For thermostats with­
out "occupied " and "unoccupied" modes, a factory-in­
stalled jumper across terminals R and OC should be in
place.
primary voltage taps as
shown in figure 4, while
460 (G) and 575 (J)
voltage transformers
use a single primary
voltage tap.
Page 15
5-Condenser Fan Capacitors C1 & C2
Fan capacitors C1 and C2 are used to assist in the start up of
condenser fans B4 and B5. Ratings will be on side of capaci­
tor or outdoor fan motor nameplate.
6-Compressor Contactor K1 & K2
All compressor contactors are three‐pole‐double‐break
contactors with 24VAC coils. In all KGA units, K1 and K2
energize compressors B1 and B2 in response to thermo­
stat demand. On CE M-voltage units, contactor is CE ap­
proved by manufacturer (Siemens). See figure 5.
CONTACTOR
FIGURE 5
7-Blower Contactor K3
Blower contactor K3, used in all units, is a three‐pole‐
double‐break contactor with a 24VAC coil used to energize
the indoor blower motor B3 in response to blower demand.
K3 is energized by a thermostat cooling demand. On M-volt
CE units, the contactor is CE approved by manufacturer
(Siemens). See figure 5.
8-Condenser Fan Relay K10
Outdoor fan relay K10 is a DPDT relay with a 24VAC coil. K10
energizes condenser fans B4 and B5.
9-Power Exhaust Relay K65 (PED units)
Power exhaust relay K65 is a DPDT relay with a 24VAC
coil. K65 is used in all KGA units equipped with the op­
tional power exhaust dampers. K65 is energized by the
economizer enthalpy control A6, after the economizer
dampers reach 50% open (adjustable) When K65
closes, exhaust fan B10 is energized.