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The cooling operation described in item 3. above also ap-
plies to operation with a dehumidification thermostat.. 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 continue running at low- -cool
speed (same speed as LO HEAT).
b. High cooling - - When the R- -to- -G- -and- -Y/Y2 circuit is
closed and there is a demand for dehumidification,the fur-
nace blower motor BLWM will drop the blower speed
from COOL to HI HEAT for a maximum of 10 minutes
before reverting back to COOL speed. If there is still a de-
mand for dehumidification after 20 minutes, the furnace
control CPU will drop the blower speed back to HI HEAT
speed. This alternating 10- -minute cycle will continue as
long as there is a call for cooling.
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 sec to 5 sec.
5. Continuous Blower Mode
When the R- -to- -G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous- -blower
speed (can be set to LO HEAT, HI HEAT, or COOL speed).
Factory default is LO HEAT speed. Terminal EAC- -1 is en-
ergized as long as the blower motor BLWM is energized.
During a call for heat, the blower BLWM will stop during
igniter warm- -up (17 sec), ignition (7 sec), and blower- -ON
delay (45 sec in low- -heat, and 25 sec in high- -heat), allow-
ing the furnace heat exchangers to heat up more quickly,
then restarts at the end of the blower- -ON delay period at
LO HEAT or HI HEAT speed respectively. The blower mo-
tor BLWM will revert to continuous- -blower speed after the
heating cycle is completed. In high- -heat, the furnace control
CPU will hold the blower motor BLWM at HI HEAT speed
during the selected blower- -OFF delay period before revert-
ing to continuous- -blower speed.
When the thermostat "calls for low- -cooling", the blower
motor BLWM will switch to operate at low- -cool speed
(same speed as LO HEAT). When the thermostat is satisfied,
the blower motor BLWM will operate an additional 90 sec
on low- -cool speed before reverting back to continuous- -
blower speed.
When the thermostat "calls for high- -cooling", the blower
motor BLWM will operate at COOL speed. When the ther-
mostat is satisfied, the blower motor BLWM will operate an
additional 90 sec on COOL speed before reverting back to
continuous- -blower speed.
When the R- -to- -G circuit is opened, the blower motor
BLWM will continue operating for an additional 5 sec, if no
other function requires blower motor BLWM operation.
Continuous Blower Speed Selection from Thermostat To
select different continuous- -blower speeds from the room
thermostat, momentarily turn off the FAN switch or push
button on the room thermostat for 1- -3 sec after the blower
motor BLWM is operating. The furnace control CPU will
shift the continuous- -blower speed from the factory setting
of LO HEAT to HI HEAT speed. Momentarily turning off
the FAN switch again at the thermostat will shift the contin-
uous- -blower speed from HI HEAT to COOL. Repeating the
procedure will shift the continuous- -blower speed from
COOL to LO HEAT speed. The selection can be changed as
many times as desired and is stored in the memory to be
automatically used following a power interruption.
NOTE:
If the blower- -off delay is set to the maximum, the
adjustable continuous- -fan feature is locked (i.e., fan speed cannot
be changed from its current setting).
6. Heat Pump
See Fig. 38 and 39 for thermostat connections.
When installed with a heat pump, the furnace control auto-
matically changes the timing sequence to avoid long blower
off times during demand defrost cycles. When the R- -to- -
W/W1- -and- -Y1 or R- -to- -W/W1- -and- -Y1- -and- -G circuits
are energized the furnace control CPU will switch to or turn
on the blower motor BLWM at low- -cool speed (same speed
as LO HEAT), and begin a low- -heat cycle. The blower mo-
tor BLWM will remain on until the end of the prepurge pe-
riod, then shut off for 24 sec then come back on at LO
HEAT speed. When the W/W1 input signal disappears, the
furnace control begins a normal inducer post- -purge period
and the blower remains running at LO HEAT speed. If the
R- -to- - W/W1- -and- -Y1- -and- -G signals disappear at the same
time, the blower motor BLWM will remain on for the se-
lected blower- - OFF delay period. If the R- -to- -W/W1- -and- -
Y1 signals disappear, leaving the G signal, the blower mo-
tor BLWM will remain on for the selected blower- -OFF
delay period then switch to continuous- -blower speed.
When the R- -to- -W/W1- -and- -Y/Y2, R- -to- -W/W1- -and- -
Y/Y2- - and- -G, R- -to- -W/W1- -and- -Y1- -and- -Y/Y2, or R- -to- -
W/W1- -and- - Y1- -and- -Y/Y2- -and- -G circuits are energized
the furnace control CPU will switch to or turn on the blower
motor BLWM at COOL speed, and begin a high- -heat cycle.
The blower motor BLWM will remain on until the end of
the prepurge period, then shut off for 24 sec then come back
on at HI HEAT speed. When the W/W1 input signal disap-
pears, the furnace control begins a normal inducer post- -
purge period and the blower switches to COOL speed after
a 3 sec delay. If the R- -to- -W/W1- -and- -Y/Y2- -and- -G or
R- -to- -W/W1- -and - -Y1- -and- - Y/Y2- -and- -G signals disap-
pear at the same time, the blower motor BLWM will remain
on for the selected blower- -OFF delay period. If the R- -to- -
W/W1- - and- -Y/Y2 or R- -to- -W/W1- - and- -Y1- -and- -Y/Y2
signals disappear, leaving the G signal, the blower motor
BLWM will remain on for the selected blower- - OFF delay
period then switch to continuous- -blower speed.
Component Self- - Test
Refer to page 73 for instructions.
82
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