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D- Once demand is met, motor runs at 50% for 30 sec-
onds.
E- Motor ramps down to stop.
A
B
OFF
OFF
E
1/2 MIN
50% CFM
COOLING DEMAND
7 1/2 MIN
82% CFM
100%
CFM
1/2 MIN
50% CFM
Application
UPFLOW DRAIN PAN
EXPANSION VALVE
COIL
BLOWER COMPARTMENT
CONTROL BOX
ELECTRIC HEAT
FIGURE 2. Typical Unit Parts Arrangement
All major blower coil components must be matched ac-
cording to Lennox recommendations for the unit to be
covered under warranty. Refer to the Product Specica-
tion bulletin for approved system matchups. A misapplied
system will cause erratic operation and can result in early
unit failure.
The units come with factory installed check and expan-
sion valve for all applications. The TXV valve has been
installed internally for a cleaner installation and is acces-
sible if required.
Unit Components
CONTROL BOX
The CBA25UHV control box is located above the blower
section shown in gure 2. Line voltage and electric heat
connections are made in the control box. Optional electric
heat ts through an opening located in the center of the
control box. When electric heat is not used, cover plates
cover the opening. The electric heat control arrangement
is detailed in the electric heat section of this manual.
TRANSFORMER
All CBA25UHV series units use a single line voltage to
24VAC transformer mounted in the control box. The
transformer supplies power to the control circuits in the
indoor and outdoor unit. Transformers are rated at 40VA.
208/240VAC single phase transformers use two primary
voltage taps as shown in gure 3.
BLUE
YELLOW
ORANGE
RED
BLACK
240 VOLTS
208 VOLTS
PRIMARY
SECONDARY
FIGURE 3. 208 / 240 Volt Transformer
BLOWER RELAY
All CBA25UHV units use a double-pole single-throw
(DPST) switch relay to energize the blower motor. The
relay coil is energized by blower demand from indoor
thermostat. When the coil is energized, a set of normally
open (N.O.) contacts closes to energize the blower motor
on cooling speed. When de-energized, a set of normal-
ly closed (N.C.) contacts allows the electric heat relay to
energize the blower on heating speed (refer to unit wiring
diagram).
BLOWER MOTOR (B3)
CBA25UHV -018, -024, -030, -036 and -048 units use sin-
gle-phase direct drive blower motors. Figure 4 shows the
parts arrangement.
All units are factory wired for heat pump and cooling ap-
plications with or without electric heat. The unit wiring dia-
grams will provide factory set blower speeds.
FIGURE 4. Blower Assembly
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