I-Unit Components; A-Control Box Components - Lennox ELP Series User Manual

I-UNIT COMPONENTS

The ELP090/120 components are shown in figures on
page 4.

A-CONTROL BOX COMPONENTS

The ELP090/120 control box components are shown in
figure 1.
ELP090/120 CONTROL PANEL
FIGURE 1
1 - Transformer T1
All ELP models use a single line voltage to 24VAC trans-
former mounted in the control box. Transformer T1 sup-
plies power to control circuits in the ELP unit. The trans-
former is rated at 70VA and is protected by a 3.5 amp
circuit breaker (CB8). CB8 is internal to the transformer.
The 208/230 (Y) voltage transformers use two primary
voltage taps as shown in figure 2, while 460 (G) and 575
(J) voltage transformers use a single primary voltage tap.
208/230V TRANSFORMER
BLUE
SECONDARY
ORANGE
FIGURE 2
NOTE – 208 volt units are field wired with the red wire
connected to control transformer. 230 volt units are factory
wired with the orange wire connected to control transform-
er primary.
2 - Outdoor Fan Capacitors C1 and C2
All ELP units use single-phase condenser fan motors. Mo-
tors are equipped with a fan run capacitor to maximize
motor efficiency. Outdoor fan capacitors C1 and C2 assist
in the start up of condenser fan motors B4 and B5. Capac-
itor ratings are on outdoor fan motor nameplates.
YELLOW
208 VOLTS
RED
230 VOLTS
PRIMARY
BLACK
3 - Compressor Contactor K1 (all units)
All compressor contactors are three-pole-double break
contactors with a 24V coil. K1 energizes compressor B1
in both ELP090 and ELP120 units. The contactor is ener-
gized from indoor thermostat terminal Y when thermostat
demand is present.
4 - Transfer Relay K8
Transfer relay K8 ensures that the indoor blower will op-
erate during all modes of operation. K8 also completes
the circuit to Y1 on the defrost control board CMC1. When
there is a demand for cooling, K8-1 closes, completing
the Y1 circuit to defrost control board CMC1 terminal
Y1. K8-2 normally closed contacts ensure an unbroken
circuit between indoor thermostat "G" and indoor blow-
er contactor through terminals "G" and "G1" on terminal
strip TB14. When there is a heat demand, normally closed
K8-1 opens, breaking the Y1 circuit to the defrost control
CMC1. Power is sent to the "RESET" coil on K6. K6-1
opens, de-energizing the reversing valve. K8-2 closes,
sending voltage from "G1" to the indoor blower control.
5 - Terminal Strip TB14 (all units)
TB14 terminal strip distributes 24V power from the ther-
mostat to control box components.
6 - CMC1 Defrost System
The defrost system includes a defrost thermostat and a
defrost control.
DEFROST THERMOSTAT
The defrost thermostat is located on the liquid line between
the check/expansion valve and the distributor. When the
defrost thermostat senses 42°F (5.5°C or cooler, its con-
tacts close and send a signal to the defrost control board
to start the defrost timing. It also terminates defrost when
the liquid line warms up to 70°F (21°C.
DEFROST CONTROL
The defrost control board includes the combined functions
of a time/temperature defrost control, defrost relay, time
delay, diagnostic LEDs, and a terminal strip for field wiring
connections.
The control provides automatic switching from normal
heating operation to defrost mode and back. During com-
pressor cycle (defrost thermostat is closed, calling for de-
frost, the control accumulates compressor run times at 30,
60, or 90 minute field adjustable intervals. If the defrost
thermostat is closed when the selected compressor run
time interval ends, the defrost relay is energized and de-
frost begins.
DEFROST CONTROL TIMING PINS
Each timing pin selection provides a different accumulat-
ed compressor run time period for one defrost cycle. This
time period must occur before a defrost cycle is initiat-
ed. The defrost interval can be adjusted (T1–30, T2–60,
T3–90). The maximum defrost period is 14 minutes and
cannot be adjusted.
NOTE – Defrost control part number is listed near the P1
timing pins. Units with defrost control 100269-04 have a
factory default setting of 90 minutes.
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