Lennox International Inc. o23v - Manual (Page 4)

Page 4
Factory settings for the blower speed jumpers are given in
the wiring diagram. Use tables 1, 2 and 3 to determine the
correct air volume for operation in heat and cool mode.
The CFM LED located on the blower control board flashes
one time per 100 cfm to indicate selected blower speed.
For example, if the unit is operating at 1000 CFM, CFM
LED will flash 10 times.
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. Read through
the jumper settings section before adjusting the jumper to
obtain the appropriate blower speed.
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 (see figure 2).
After the CFM for each application has been deter-
mined, the jumper settings must be adjusted to reflect
those given in tables 1, 2 and 3. From the tables, deter-
mine which row most closely matches the desired CFM.
Once a specific row has been chosen (+, NORMAL, or
−), CFM volumes from other rows cannot be used.
Page 5 has descriptions of the jumper selections.
The variable speed motor slowly ramps up to and down
from the selected air flow during both cooling and heat-
ing demand. This minimizes noise and eliminates the
initial blast of air when the blower is initially energized.
Blower Control Board (A54)
16−PIN PLUG
(BOARD TO MOTOR)
DIAGNOSTIC LED
ADJUST
SELECTOR PINS
(Setting affect cooling
only)
HEATING SPEED
SELECTOR PINS (SEE
TABLE)
COOLING SPEED
SELECTOR PINS
NOTE − The JW1 resistor
must be cut to activate the
HUM terminal.
O23V−Q2/3−090
O23V−Q3/4−120
O23V−Q2/3−070
O23V−Q3/4−105
O23V−Q5−140
O23V−Q5−154
HEAT SPEED SELECTOR
PINS (JUMPERS)
FIGURE 2