Page 14
ADJUST
The
ADJUST
pins allow the motor to run at normal speed,
approximately 15% higher than normal speed, or 15% low-
er than normal speed. Table 6 gives three rowsNORM,
(+), and (–) with their respective CFM volumes. Notice that
the normal NORM" adjustment setting for cool speed
position C in table 6 is 800 CFM. The (+)" adjustment set-
ting for that position is 920 CFM (115% of 800 CFM) and
the (–)" adjustment setting is 680 CFM (85% of 800 CFM).
After the adjustment setting has been determined, choose
the remaining speed settings from those offered in the
table in that row.
The TEST pin is available to bypass the blower control and
run the motor at approximately 70% to make sure that the
motor is operational. This is used mainly in troubleshoot-
ing. The G terminal must be energized for the motor to run.
COOL (single-stage systems)
The
COOL
jumper is used to determine the CFM during
cooling operation. This jumper selection is activated for
cooling when Y1 is energized. Y1 and Y2 must be jump-
ered for single stage cooling.
The blower motor runs at 82% CFM for the first 7−1/2 min-
utes of each cooling demand to allow for greater humidity
removal and to conserve energy. If, after 7−1/2 minutes,
the Y demand is not met, 100% CFM is supplied until the
demand is satisfied.
OFF
CALL
100%
82%
Y
60
sec
7.5 minutes
82%
y
Y − Cool Demand Present
y − Cool Demand Satisfied
When the demand for cool is met, the blower ramps down
to 82% CFM for 60 seconds, then turns off.
COOL (two-stage systems)
IMPORTANT
The unit is factory set for single−stage cooling. For
two−stage cooling operation, the jumper wire from
Y1 to Y2 on the blower control board must be cut (at
terminal Y1) and connected to Y2 from the thermo-
stat (A54 board Y2" to thermostat Y2"). See figure
18 wiring diagram.
A thermostat call for first-stage cooling closes the R to Y1
circuit on the A54 blower control board. The blower motor
runs at 57% CFM for the first 7−1/2 minutes of the 1st−stage
cooling demand. After 7−1/2 minutes, the blower motor
runs at 70% CFM until the first−stage demand is satisfied.
OFF
CALL
100%
70%
57%
Y1
7−1/2
minutes
60
sec
y2/Y1
Y1 − 1st−stage COOL Demand Present
y1 − 1st−stage COOL Demand Satisfied
Y2 − 2nd−stage COOL Demand Present
y2 − 2nd−stage COOL Demand Satisfied
Y1/Y2
70%
57%
y1
y1
OFF
60
sec
If first−stage cooling does not satisfy the demand, the ther-
mostat calls for 2nd-stage cooling, closing the R to Y2 cir-
cuit on the A54 blower control board. The blower motor
ramps up to 100% CFM.
When the Y2 demand is met, the blower ramps down to Y1
at 70% CFM until Y1 is met, and ramps down to 57% CFM
for 1 minute, then turns off.
HEAT
The unit is factory−set to run at the middle of heating rise
range as shown on the unit rating plate. The jumper on the
tap marked
HEAT
should remain in the position (A, B, D, or
D) as shown in the HEATING SPEED SELECTOR PINS
graphic found in the wiring diagram (figure 18).
The
HEAT
jumper is used to determine CFM during gas
heat operation only. These jumper selections are activated
only when W1 is energized.
During the heat ON delay, the blower runs at 13% CFM for
the first minute, 50% CFM for the second minute, and full
CFM after two minutes.
OFF
CALL
100%
82%
50%
13%
W
60
sec
60
sec
210 seconds
w
W − Heat Demand Present
w − Heat Demand Satisfied
When the demand for heat is met, the blower ramps down
to 82% CFM for 3−1/2 minutes, then turns off.
Heat Pump
IMPORTANT
For heat pump operation, cut the jumper between R
and O near the R terminal of A54 and connect the
pigtail to the thermostat O wire (A54 board O" to
thermostat O"). See figure 18 wiring diagram.
In heat pump mode, a call for heat pump operation follows
the same sequence as a call for cooling, with the exception
that there is a 30−second blower ramp−up to blower CFM.
Downloaded from
