Model Number Information; Adjusting The Bdc3 Blower Control; Adjusting The Blower Speed - Lennox CBX25UHV Series Installation And Service Procedure

MODEL NUMBER IDENTIFICATION
CB - Air Handler
Refrigerant Type
X = HFC-410A
UHV = Up-Flow / Horizontal, Variable
CAUTION
Electrostatic discharge can affect electronic compo­
nents. Take precautions during unit installation and
service to protect the unit's electronic controls. Pre­
cautions will help to avoid control exposure to electro­
static discharge by putting the unit, the control and
the technician at the same electrostatic potential.
Neutralize electrostatic charge by touching hand and
all tools on an unpainted unit surface before perform­
ing any service procedure.

Adjusting the BDC3 Blower Control

JP1 15 PIN
PLUG (BOARD
TO MOTOR)
QC1
24V ACCESSORY
SERVICE
CONTACTS –
RATED FOR 1 AMP 24V/1A
OR LESS
QC2
NOR
M
+
OPERATIONAL
-
SELECTOR PINS
TES
(AFFECTS BOTH
T
HEATING AND
ADJUST
COOLING MODES)
HEATING SPEED
SELECTOR PINS
COOLING SPEED
SELECTOR PINS
Figure 1. BDC3 Variable Speed Control Selections
CB X 25 UHV - 030 - 230 - 1
Unit Type
Series
Configuration
Speed Blower Motor
JP1
4 4 4
3 3 3
2 2 2
1 1 1
HEAT COOL DELAY CFM RUN
DIAGNOSTIC
LEDS
FAN DELAY
SELECTOR PINS
Voltage
230 = 208/230V-1 phase-60hz
Nominal Cooling Capacity
018 = 1.5 tons
024 = 2 tons
030 = 2.5 tons
036 = 3 tons
042 = 3.5 tons
048 = 4 tons
060 = 5 tons
CBX25UHV units are equipped with a variable-speed
motor that is capable of maintaining a specified CFM
throughout the external static range. A particular CFM can
be obtained by positioning jumpers (COOL, HEAT, and
ADJUST) on the BDC3 control.
The jumpers are labeled 1, 2, 3, and 4. This indicates the
selected air volume (CFM). The ADJUST jumper is labeled
Test, -, +, and Norm. The - and + pin settings are used to add
or subtract a percentage of the CFM selected. The Test
jumper is used to operate the motor in the test mode. The
delay jumper controls the timing pattern in which the fan
delay occurs.
Figure 1 illustrates the BDC3 control. Use either table 4 on
page 7, or table 5 on page 7 to determine the correct air
volume for heat and cool speed taps.
Diagnostic LEDs located on the BDC3 control are provided
to aid in identifying the unit's mode of operation. Certain
scenarios will arise depending on the jumper positions.
Read through the jumper settings sections before adjusting
blower speed. Refer to figure 1 on page 5 for identification.

Adjusting the Blower Speed

Diagnostic LEDs
1. RUN LED indicates there is a demand for the blower
motor to run.
2. CFM LED indicates the cubic feet per minute at which
the unit is operating. The light flashes once for
approximately every 100 CFM. For example, if the unit
is operating at 1000 CFM, CFM LED will flash 10 times.
If the CFM is 1150, CFM LED will flash 11 full times plus
one fast or half flash.
At times, the light may appear to flicker or glow. This is
normal and occurs when the control is communicating with
the motor between cycles.
The appropriate speed, according to application and CFM
need, is selected by moving jumper pins.
Page 5
Minor Revision Number