BLWM to high-cooling airflow. High-cooling airflow is
based on the A/C selection shown in Table 1 and 1a.
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 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. 2 in Appendix.)
3. Two-Stage Thermostat and Two-Speed Cooling
NOTE:
The air conditioning relay disable jumper ACRDJ must
be disconnected to allow thermostat control of the outdoor unit
staging. (See Fig. 1.)
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 selection as shown in Table 1. 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 selection shown in
Table 1 and 1a.
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 addi-
tional 90 seconds. Jumper Y1 to DHUM to reduce the
cooling off-delay to 5 seconds. (See Fig. 2 in Appendix.)
Step 4—Thermidistat Mode
The dehumidification output, DHUM on the Thermidistat should
be connected to the furnace control thermostat terminal 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 3. above also applies to operation with
a Thermidistat. The exceptions are listed below:
1. 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
low-cooling airflow which is the true on-board CF selection as
shown in Table 1 and 1a.
2. 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
high-cooling airflow. High-cooling airflow is based on the
A/C selection shown in Table 1 and 1a.
3. When the
″
call for cooling
″
is satisfied and there is a demand
for dehumidification, the cooling blower-off delay is de-
creased from 90 seconds to 5 seconds.
Step 5—Super-Dehumidify Mode
Super-Dehumidify mode can only be entered if the furnace control
is in the Thermidistat mode and there is a demand for dehumidi-
fication. The cooling operation described in item 3. above also
applies to operation with a Thermidistat. The exceptions are listed
below:
1. When the R to Y1 circuit is closed, R to G circuit is open, and
there is a demand for dehumidification, the furnace blower
motor BLWM will drop the blower airflow to 65 percent of
low-cooling airflow for a maximum of 10 minutes each
cooling cycle or until the R to G circuit closes or the demand
for dehumidification is satisfied. Low-cooling airflow is the
true on-board CF selection as shown in Table 1 and 1a.
2. When the R to Y/Y2 circuit is closed, R to G circuit is open,
and there is a demand for dehumidification, the furnace
blower motor BLWM will drop the blower airflow to 65
percent of high-cooling airflow for a maximum of 10 minutes
each cooling cycle or until the R to G circuit closes or the
demand for dehumidification is satisfied. High-cooling air-
flow is based on the A/C selection shown in Table 1 and 1a.
3. When the
″
call for cooling
″
is satisfied and there is a demand
for dehumidification, the cooling blower-off delay is de-
creased from 90 seconds to 5 seconds.
Step 6—Continuous Blower Mode
When the R to G circuit is closed by the thermostat, the blower
motor BLWM will operate at continuous blower airflow. Continu-
ous blower airflow selection is initially based on the CF selection
shown in Table 1 and 1a. Factory default is shown in Table 1 and
1a. Terminal EAC-1 is energized as long as the blower motor
BLWM is energized.
During a call for heat, the furnace control CPU will transition the
blower motor BLWM to continuous blower airflow, low-heat
airflow, or the midrange airflow, whichever is lowest. The blower
motor BLWM will remain ON until the main burners ignite then
shut OFF and remain OFF for the blower-ON delay (60 seconds in
low-heat, and 35 seconds in high-heat), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the end of the
blower-ON delay period at low-heat or high-heat airflow respec-
tively.
The blower motor BLWM will revert to continuous-blower airflow
after the heating cycle is completed. In high-heat, the furnace
control CPU will drop the blower motor BLWM to low-heat
airflow during the selected blower-OFF delay period before
transitioning to continuous-blower airflow.
When the thermostat
″
calls for low-cooling
″
, the blower motor
BLWM will switch to low-cooling airflow. When the thermostat is
satisfied, the blower motor BLWM will operate an additional 90
seconds at low-cooling airflow before transitioning back to
continuous-blower airflow.
When the thermostat
″
calls for high-cooling
″
, the blower motor
BLWM will switch to high cooling airflow. When the thermostat
is satisfied, the blower motor BLWM will operate an additional 90
seconds at high-cooling airflow before transitioning back to
continuous-blower airflow.
When the R to G circuit is opened, the blower motor BLWM will
continue operating for an additional 5 seconds, if no other function
requires blower motor BLWM operation.
•
Continuous Blower Speed Selection from Thermostat
To select different continuous-blower airflows from the room
thermostat, momentarily turn off the FAN switch or push-
button on the room thermostat for 1-3 seconds after the blower
motor BLWM is operating. The furnace control CPU will shift
6
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