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additional 90 seconds. Jumper Y/Y2 to DHUM to
reduce the cooling off-delay to 5 seconds. (See Fig. 31.)
b. Two-Speed Cooling
(See Fig. 49, 51, 53, and 54 for thermostat
connections.)
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 on low-cool speed (same speed as FAN). 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 on COOL
speed.
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. 31.)
THERMIDISTAT MODE
(See Fig. 48 - - 51 for Thermidistat connections.)
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. When 24 vac is initially detected by the furnace
control on the DHUM input, the furnace control operates in
Thermidistat mode. If the DHUM input is low or OFF for more
than
48
hours,
the
furnace
non-Thermidistat mode.
The cooling operation described in item 2. above also applies to
operation with a Thermidistat. The exceptions are listed below:
a. When the R to G-and-Y1 circuit is closed and there is
a demand for dehumidification, the furnace blower
motor BLWM will continue running at low-cool speed
(same speed as FAN).
b. 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 speed from COOL
to HEAT for a maximum of 10 minutes before
reverting back to COOL speed. If there is still a
demand for dehumidification after 20 minutes, the
furnace control CPU will drop the blower speed back
to HEAT speed. This alternating 10-minute cycle will
continue as long as there is a call for cooling.
c. When the "call for cooling" is satisfied while there is a
demand for dehumidification, the cooling blower-off
delay is decreased from 90 seconds to 5 seconds.
control
reverts
back
to
- - 49 - -
Fig. 48 - - Single-Stage Furnace with Single-Speed
Air Conditioner
Fig. 49 - - Single Stage Furnace with Two-Speed
Air Conditioner
A00268
A00269
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