507148-01
Page 12 of 14
Issue 1406
as long as there is a call for dehumidification.
Single Stage Cooling (see Figure 14)
A call for cooling from the thermostat closes the R to Y
circuit on the blower interface board. The control waits
for a 1-second delay before energizing the circulating
blower to 82% of the selected cooling CFM (passive
dehumidification mode). After 7.5 minutes, the circulating
blower automatically ramps up to 100% of the selected
cooling airflow. When the call for cooling is satisfied, the
Heating
Figure 13
W
w
100%
82%
3.5 min
CALL
OFF
W - Heat Demand Present
- Heat Demand Satisfied
w
13%
50%
1
min
1
min
7.5 minutes
Y
y
82%
100%
82%
1
min
CALL
OFF
Y - Cool Demand Present
- Cool Demand Satisfied
y
Single Stage Cooling
Figure 14
circulating blower ramps back down to 82% of the selected
cooling airflow for 1 minute, then shuts off.
Two Stage Cooling (see Figure 15)
A call for 1
st
stage cooling from the thermostat closes the
R to Y1 circuit on the blower interface board. The control
waits for a 1-second delay before energizing the circulating
blower. The blower motor runs at 57% of the selected air
flow for the first 7.5 minutes of the 1
st
stage cooling demand
(passive dehumidification mode). After 7.5 minutes, the
blower motor runs at 70% of the selected cooling air flow
until 1
st
stage cooling demand is satisfied.
A call for 2
nd
stage cooling from the thermostat closes the
R to Y2 circuit on the blower interface board. The blower
motor ramps up to 100% of the selected cooling air flow.
When the demand for cooling is met, the blower ramps
down to Y1 until satisfied, then ramps down to 57% for 1
minute, then turns off.
Heat Pump
For heat pump operation, clip the jumper wire between R and
O. 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.
Continuous Fan (see Figure 16)
When the thermostat is set for continuous fan operation and
there is no demand for heating or cooling, a call for fan closes
the R to G circuit and the circulating blower motor runs at 50%
of the selected cooling CFM until switched off.
Continuous Fan
Figure 16
G
g
50%
CALL
OFF
G - Fan Switch ON
- Fan Switch OFF
g
Two Stage Cooling
Figure 15
Y1
y1
57%
100%
CALL
OFF
7.5
minutes
70%
Y1 - 1 Stage Cool Demand Present
st
-
Demand Satisfied
1 Stage Cool
st
y1
Y2 - 2 Stage Cool Demand Present
nd
- 2
Demand Satisfied
nd
Stage Cool
y2
1
min
70%
Y1 y2
/
Y1
/
Y2
y1
57%
1
min
57%
The system must not be in either the passive or active
dehumidification mode when charging a cooling system.
IMPORTANT
