Page 6
BLOWER CONTROL BOARD (A54)
16−PIN PLUG
(BOARD TO MOTOR)
ADJUST
SELECTOR PINS
(Setting affects both
heating and cooling
modes)
DIAGNOSTIC
LED
HEATING SPEED
SELECTOR PINS
COOLING SPEED
SELECTOR PINS
FIGURE 4
COOL
The
COOL
jumper is used to determine the CFM during
cooling operation. This jumper selection is activated for
cooling when Y1 is energized.
The blower motor runs at 80 percent of the selected air flow
for the first 7−1/2 minutes of each cooling demand. This fea-
ture allows for greater humidity removal and saves energy.
In the cooling mode, the blower control board delays blower
operation for 5 seconds after the compressor starts. The
blower continues to operate for 90 seconds after the
compressor is de−energized.
HEAT
The
HEAT
jumper is used to determine CFM during backup
electric heat operation only. These jumper selections are
activated only when W is energized.
In the backup heat mode, the blower continues to operate
for 2 minutes after the heating demand is satisfied.
NOTE − Due to the nature of electric heat, CFM settings are
limited.
CONTINUOUS FAN
When the thermostat is set for Continuous Fan" operation
and there is no demand for heating or cooling, the blower
control will provide 50 percent of the
COOL
CFM selected.
NOTE − With the proper thermostat and subbase, continu-
ous blower operation is possible by closing the R to G cir-
cuit. Cooling blower delay is also functional in this mode.
DEHUMIDIFICATION
The blower control board includes an HUM terminal which
provides for connection of a humidistat. The JV1 resistor on
the blower control board must be cut to activate the HUM
terminal. The humidistat must be wired to open on humidity
rise. When the dehumidification circuit is used, the variable
speed motor will reduce the selected air flow rate by 25 per-
cent when humidity levels are high. An LED (D1) lights
when the blower is operating in the dehumidification mode.
