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ing on selection at blower- -OFF delay switches). The
furnace control CPU is factory- -set for a 120- -second
blower- -OFF delay.
2. Cooling mode
The thermostat "calls for cooling".
a. Single- -Speed Cooling- -
See Fig. 25 for thermostat connections
The thermostat closes the R- -to- -G- -and- -Y circuits. The
R- -to- - Y circuit starts the outdoor unit, and the R- -to- -
G- -and- -Y/Y2 circuits start the furnace blower motor
BLWM on cooling airflow. Cooling airflow is based
on the A/C selection shown in Fig. 42. The electronic
air cleaner terminal EAC- -1 is energized with 115 vac
when the blower motor BLWM is operating.
When the thermostat is satisfied, the R- -to- -G- -and- -Y
circuits are opened. The outdoor unit will stop, and the
furnace blower motor BLWM will continue operating
at cooling airflow for an additional 90 seconds.
Jumper Y/Y2 to DHUM to reduce the cooling off- -de-
lay to 5 seconds. (See Fig. 23)
b. Single- -Stage Thermostat and Two- -Speed Cooling
(Adaptive Mode)
See Fig. 28 for thermostat connections.
This furnace can operate a two- -speed cooling unit
with a single- -stage thermostat because the furnace
control CPU includes a programmed adaptive se-
quence of controlled operation, which selects low- -
cooling or high- -cooling operation. This selection is
based upon the stored history of the length of previous
cooling period of the single- -stage thermostat.
NOTE: The air conditioning relay disable jumper ACRDJ must
be connected to enable the adaptive cooling mode in response to
a call for cooling. (See Fig. 23) When ACRDJ is in place the
furnace control CPU can turn on the air conditioning relay ACR
to energize the Y/Y2 terminal and switch the outdoor unit to
high- -cooling.
The furnace control CPU can start up the cooling unit in either
low- - or high- -cooling. If starting up in low- -cooling, the furnace
control CPU determines the low- -cooling on- -time (from 0 to 20
minutes) which is permitted before switching to high- -cooling. If
the power is interrupted, the stored history is erased and the
furnace control CPU will select low- -cooling for up to 20 minutes
and then energize the air conditioning relay ACR to energize the
Y/Y2 terminal and switch the outdoor unit to high- -cooling, as
long as the thermostat continues to call for cooling. Subsequent
selection is based on stored history of the thermostat cycle times.
The
wall
thermostat
"calls
R- -to- -G- -and- -Y circuits. The R- -to- -Y1 circuit starts the outdoor
unit on low- -cooling speed, and the R- -to- -G- -and- -Y1 circuits
starts the furnace blower motor BLWM at low- -cooling airflow
which is the true on- -board CF selection as shown in Fig. 42.
If the furnace control CPU switches from low- -cooling to
high- -cooling, the furnace control CPU will energize the air
conditioning relay ACR. When the air conditioning relay ACR is
energized the R- -to- -Y1- -and- -Y2 circuits switch the outdoor unit
to high- -cooling speed, and the R- -to- -G- -and- -Y1- -and- -Y/Y2
circuits transition the furnace blower motor BLWM to
high- -cooling airflow. High- -cooling airflow is based on the A/C
selection shown in Fig. 42.
NOTE: When transitioning from low- -cooling to high- -cooling
the outdoor unit compressor will shut down for 1 minute while
the furnace blower motor BLWM transitions to run at
high- -cooling airflow.
The electronic air cleaner terminal EAC- -1 is energized with 115
vac whenever the blower motor BLWM is operating.
When the thermostat is satisfied, the R- -to- -G- -and- -Y circuit are
opened. The outdoor unit stops, and the furnace blower BLWM
for
cooling",
closing
the
and electronic air cleaner terminal EAC- -1 will remain energized
for an additional 90 seconds. Jumper Y1 to DHUM to reduce the
cooling off- -delay to 5 seconds. (See Fig. 23)
c. Two- -Stage Thermostat and Two- -Speed Cooling
See Fig. 26 for thermostat connections
NOTE: The air conditioning relay disable jumper ACRDJ must
be disconnected to allow thermostat control of the outdoor unit
staging. (See Fig. 23)
The thermostat closes the R- -to- -G- -and- -Y1 circuits for
low- -cooling or closes the R- -to- -G- -and- -Y1- -and- -Y2 circuits for
high- -cooling. The R- -to- -Y1 circuit starts the outdoor unit on
low- -cooling speed, and the R- -to- -G- -and- -Y1 circuit starts the
furnace blower motor BLWM at low- -cooling airflow which is the
true on- -board CF (continuous fan) selection as shown in Fig. 42.
The R- -to- -Y1- -and- -Y2 circuits start the outdoor unit on
high- -cooling speed, and the R- -to- - G- -and- -Y/Y2 circuits start the
furnace blower motor BLWM at high- -cooling airflow.
High- -cooling airflow is based on the A/C (air conditioning)
selection shown in Fig. 42.
The electronic air cleaner terminal EAC- -1 is energized with 115
vac whenever the blower motor BLWM is operating.
When the thermostat is satisfied, the R- -to- -G- -and- -Y1 or R- -to- -
G- -and- -Y1- -and- -Y2 circuits are opened. The outdoor unit stops,
and the furnace blower BLWM and electronic air cleaner terminal
EAC- -1 will remain energized for an additional 90 seconds.
Jumper Y1 to DHUM to reduce the cooling off- -delay to 5
seconds. (See Fig. 23)
3. Thermidistat Mode
See Fig. 25- -27 for thermostat connections.
The dehumidification output, DHUM on the Thermidistat
should be connected to the furnace control thermostat ter-
minal DHUM. When there is a dehumidify demand, the
DHUM input is activated, which means 24 vac signal is
removed from the DHUM input terminal. In other words,
the DHUM input logic is reversed. The DHUM input is
turned ON when no dehumidify demand exists. Once 24
vac is detected by the furnace control on the DHUM input,
the furnace control operates in Thermidistat mode. If the
DHUM input is low for more than 48 hours, the furnace
control reverts back to non- -Thermidistat mode.
The cooling operation described in item 2. above also ap-
plies to operation with a Thermidistat. The exceptions are
listed below:
a. Low cooling- -When the R- -to- -G- -and- -Y1 circuit is
closed and there is a demand for dehumidification, the
furnace blower motor BLWM will drop the blower
airflow to 86 percent of cooling airflow which is the
true on- -board CF (continuous fan) selection as shown
in Fig. 42.
b. High cooling- -When the R- -to- -G- -and Y/Y2 circuit is
closed and there is a demand for dehumidification, the
furnace blower motor BLWM will drop the blower
airflow to 86 percent of cooling airflow. Cooling air-
flow is based on the A/C (air conditioning) selection
shown in Fig. 42.
c. Cooling off- -delay- -When the "call for cooling" is
satisfied and there is a demand for dehumidification,
the cooling blower- -off delay is decreased from 90
seconds to 5 seconds.
4. Super- -Dehumidify Mode
Super- -Dehumidify mode can only be entered if the fur-
nace control is in the Thermidistat mode and there is a de-
mand for dehumidification. The cooling operation de-
scribed in item 3. above also applies to operation with a
Thermidistat. The exceptions are listed below:
a. When the R- -to- -Y1 circuit is closed, R- -to- -G circuit is
open, and there is a demand for dehumidification, the
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