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the BDC3 control board. The jumpers are labeled 1, 2, 3,
and 4. Each of the numbers corresponds with an air
volume (CFM) setting. The ADJUST jumper is labeled
Test, −, +, and Norm. The + and − pin settings are used to
CB31MV
Condensing Unit
Air Handler
−041
COOL PIN #3
−051
COOL PIN #2
−065
COOL PIN #3
*
Minimum setting for heat.
Figure 15 on page 10 provides an illustration of the BDC3
control board. Use tables 5 and 6 on page 12 to determine
the correct air volume for heat and cool speed taps.
ACCESSORY RELAY CONTACTS (DRIVES
OPTIONAL ACCESSORY RELAY)
HEATING SPEED
COOLING SPEED
SELECTOR PINS
SELECTOR PINS
OPERATIONAL SELECTOR PINS (AFFECTS
BOTH HEATING AND COOLING MODES)
Figure 15. BDC3 Variable Speed Control Board
Selections
Diagnostic LEDs located on the BDC3 control board 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 15 for
identification.
Adjusting Blower Speed
DIAGNOSTIC LEDS
Step 1.
RUN LED indicates there is a demand for the
Blower motor to run.
Step 2.
CFM LED indicates the CFM at which the unit is
operating.
The
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 takes
place when the control is communicating with the motor
between cycles. This is normal operation.
505341M 04/08
Table 4. Blower Speed Tap Selection
RECOMMENDED SPEED TAP SELECTION
COOL
Heat Pump
COOL PIN #3
COOL PIN #2
COOL PIN #3
JP1 15 PIN PLUG
(BOARD TO MOTOR)
DIAGNOSTIC
LEDS
FAN DELAY
SELECTOR PINS
light
flashes
once
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 for the fan delay.
Condensing Unit With
Electric Heat Only
HEAT PIN #4
HEAT PIN #1
HEAT PIN #1
The appropriate speed according to application and CFM
need is selected by moving jumper pins.
Before changing jumper setting, make sure the
motor has completely stopped. Any jumper setting
change will not take place while the motor is
running.
Table 4 lists the recommended factory Blower speed tap
selections for CB31MV series units. These settings are for
nominal tonnage match−ups with the CB31MV. When
matched with other sizes, it is recommended that the CFM
be adjusted to approximately 400 CFM per ton.
To change jumper positions, gently pull the jumper off the
pins and place it on the desired set of pins. The following
section outlines the different jumper selections available
and conditions associated with each one as illustrated in
figure 15.
After the CFM for each application has been determined,
the jumper settings must be adjusted to reflect those given
in tables 5 and 6. From the tables, determine which row of
CFM volumes most closely matches the desired CFM.
Once a specific row has been chosen (+, NORMAL, or −),
CFM volumes from other rows cannot be used. Below are
descriptions of the jumper selections.
ADJUST JUMPERS
The ADJUST pins allow the motor to run at normal speed,
approximately 10% higher, or approximately 10% lower than
normal speed. Table 5 gives three rows (+, NORMAL, and −)
with their respective CFM volumes. Notice that the normal
adjustment setting for heat speed position #3 is 1315 CFM.
The + adjustment setting for that position is 1445 CFM and
for the − adjustment setting is 1185 CFM. After the
for
adjustment setting has been determined, chose the
remainder speed jumper settings from those offered in the
table in that row.
The TEST pin is available to bypass the BDC3 control and
run the motor at approximately 70% to test that the motor is
operational. This is beneficial primarily in troubleshooting.
G must be energized for motor to run.
Page 10
HEAT
Heat Pump With Electric Heat
HEAT PIN #4
HEAT PIN #1
HEAT PIN #1
IMPORTANT
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