furnace blower motor BLWM on low-cooling speed
(same speed as for low-gas heat). The R to Y1-and-Y2
circuits start the outdoor unit on high-cooling speed,
and the R to G-and-Y2 circuits start furnace blower
motor BLWM on high-cooling speed.
NOTE:
Y1 is found in the outdoor unit. The furnace control CPU
controls blower motor BLWM speed by sensing only G for
low-cooling speed and Y/Y2 for high-cooling speed.
(2.) The EAC terminals EAC-1 and EAC-2 are energized
with 115v when blower motor BLWM is operating on
either cooling speed.
(3.) When thermostat is satisfied, the R to G-and-Y1 or R
to G-and-Y1-and-Y/Y2 circuits open. The outdoor
unit stops, and furnace blower continues operating on
cooling speed for an additional 90 sec.
4. Continuous Blower Mode
a. When R to G circuit is closed by thermostat, the blower
motor BLWM operates on low-gas heat speed (identical to
low-cool speed). Terminals EAC-1 and EAC-2 are ener-
gized with 115v as long as blower motor BLWM is
energized.
b. During a
″
call for heat,
″
the blower motor BLWM stops
during ignitor warm-up (17 sec), ignition (7 sec), and
blower on delay (45 sec), allowing furnace heat exchangers
to heat up quickly.
c. The blower motor BLWM reverts to continuous blower
speed after the heating cycle is completed. In high-gas heat,
the furnace control CPU holds the blower motor BLWM at
high-gas-heat speed during the selected blower off delay
period before reverting to continuous blower speed.
(1.) When thermostat
″
calls for low-cooling,
″
the blower
motor BLWM continues to operate on low-cool speed.
When thermostat is satisfied, the blower motor
BLWM continues on continuous blower speed.
(2.) When thermostat
″
calls for high-cooling,
″
the blower
motor BLWM operates on high-cool speed. When the
thermostat is satisfied, the blower motor BLWM
operates an additional 2 sec on high-cool speed before
reverting back to continuous blower speed.
(3.) When R-G circuit is opened, the blower motor BLWM
continues operating for an additional 90 sec if no other
function requires blower motor BLWM operation.
5. Heat Pump Mode
NOTE:
A dual fuel thermostat or accessory interface kit is
required with single-speed heat pumps. See dual fuel thermostat or
interface kit Installation Instructions for single-speed heat pump
thermostat and interface connections. No interface kit is needed for
2-speed heat pumps. See 2-speed heat pump Installation Instruc-
tions to determine whether a standard or dual-fuel heat pump
thermostat is required and for thermostat connections.
a. Single-Speed Heat Pump Cooling
(1.) The thermostat and interface kit close the R to
G-and-Y/Y2 circuit to start the furnace blower motor
BLWM on high-cooling speed. The Y/Y2 input to the
furnace control is necessary to provide adequate cool-
ing airflow.
(2.) The EAC terminals EAC-1 and EAC-2 are energized
with 115v when the blower motor BLWM is operat-
ing.
(3.) When thermostat is satisfied, furnace blower motor
BLWM continues operating on high-cool speed for an
additional 90 sec.
b. Two-Speed Heat Pump Cooling
(1.) The thermostat R to G circuits start the furnace blower
motor BLWM on low-cool speed. The thermostat R to
G-and-Y/Y2 circuits start the furnace blower motor
BLWM on high-cool speed.
NOTE:
The furnace control CPU controls blower motor BLWM
speed by sensing only G for low-cool speed and Y2 for high-cool
speed.
(2.) The EAC terminals EAC-1 and EAC-2 are energized
with 115v when the blower motor BLWM is operating
on either cooling speed.
(3.) When thermostat is satisfied, the furnace blower
motor BLWM continues operating on cooling speed
for an additional 90 sec.
c. Single-Speed Heat Pump Heating
(1.) The thermostat and accessory interface kit R to G-
and-Y/Y2 circuits start the furnace blower motor
BLWM on heat pump high-heat speed (identical to
high-cool speed).
(2.) The EAC terminals EAC-1 and EAC-2 are energized
with 115v when the blower motor BLWM is operat-
ing.
(3.) When thermostat is satisfied, the furnace blower motor
BLWM continues operating on heat pump high-heat
speed for an additional 90 sec.
d. Two-Speed Heat Pump Heating
(1.) The thermostat closes R-G circuit for low heat and
starts furnace blower motor BLWM on heat pump
low-heat speed (identical to low-cooling speed). Clos-
ing R-Y/Y2 circuit to furnace provides blower motor
BLWM heat pump high-heat speed.
NOTE:
The furnace control CPU controls blower motor BLWM
speed by sensing only G (for heat pump low-heat speed) and Y2
(for heat pump high-heat speed).
(2.) The EAC terminals EAC-1 and EAC-2 are energized
with 115v when the blower motor BLWM is operating
on either heating speed.
(3.) When thermostat is satisfied, the furnace blower
motor BLWM continues operating on heating speed
for an additional 90 sec.
(4.) Opening only R-Y/Y2 circuit reduces blower motor
BLWM speed to heat pump low-heat speed.
6. Defrost
a. When furnace control R to W/W1-and-Y/Y2 circuits are
closed, furnace control CPU continues blower motor
BLWM operation at heat pump heating speed until the end
of the prepurge period, then shuts off until the end of the
HSI ignitor-on period (22 sec).
b. When installed with a heat pump, the furnace control CPU
automatically holds blower off time to 22 sec during HSI
ignitor on period. After 17 sec of HSI ignitor-on period, a
trial for ignition sequence occurs as described above for
gas heating. After flame is proved and without a blower on
delay, the blower motor BLWM will operate on high-gas-
heat speed during defrost. For both single-speed and
2-speed heat pumps, defrost mode is in high-gas heat only.
c. When furnace control R-W/W1 circuit is opened, the
furnace control CPU begins the normal inducer post purge
period and the blower motor BLWM remains on for the
blower off delay period. If R-G circuit remains closed,
blower motor BLWM reverts to continuous operation.
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