45
441 01 1411 04
Specifications are subject to change without notice.
fy mode. If the DHUM input is low for more than 48
hours, the furnace control reverts back to non
−
humidity
sensing thermostat mode.
The cooling operation described in item 2. above also
applies to operation with a humidity sensing thermo-
stat. 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 de-
mand for dehumidification after 20 minutes, the fur-
nace 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 and there is a
demand for dehumidification, the cooling blower
−
OFF
delay is decreased from 90 seconds to 5 seconds.
4.
Continuous Blower Mode
When the R
−
to
−
G circuit is closed by the thermostat,
the blower motor BLWM will operate on continuous
−
blower speed (same speed as FAN). Terminal EAC 1
AMP is energized as long as the blower motor BLWM
is energized. During a call for heat, the blower BLWM
will stop during igniter warm
−
up (17 seconds), ignition
(7 seconds), and blower
−
on delay (25 seconds), allow-
ing the furnace heat exchangers to heat up more
quickly, then restarts at the end of the blower
−
on delay
period at HEAT speed.
In heating, the furnace control CPU will hold the blower
motor BLWM at HEAT speed during the selected heat
−
off delay period before reverting to continuous
−
blower
speed. When the thermostat “calls for low
−
cooling,” the
blower motor BLWM will remain operating at continu-
ous blower speed.
When the thermostat “calls for high
−
cooling”, the
blower motor BLWM will operate at COOL speed.
When the thermostat is satisfied, the blower motor
BLWM will operate an additional 90 seconds 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
seconds, if no other function requires blower motor
BLWM operation.
5.
Heat pump
(See Figure 26
−
Figure 33 for thermostat connec-
tions.) When installed with a heat pump, the furnace
control automatically changes the timing sequence to
avoid long blower off times during demand defrost
cycles. When the R
−
to
−
W
−
and
−
Y1 or R
−
to
−
W
−
and
−
Y1
−
and
−
G circuits are energized the furnace control
CPU will switch to or turn on the blower motor BLWM at
HEAT speed, and begin a heating cycle. The blower
motor BLWM will remain on until the end of the prepur-
ge period, then shut off for 24 seconds then come back
on at HEAT speed. When the W input signal disap-
pears, the furnace control begins a normal inducer
post
−
purge period and the blower remains running at
HEAT speed for the selected blower
−
OFF delay period
then switches to low
−
cool speed (same speed as
FAN). If the R
−
to
−
W
−
and
−
Y1
−
and
−
G signals disap-
pear at the same time, the blower motor BLWM will re-
main on for the selected blower
−
OFF delay period. If
the R
−
to
−
W
−
and
−
Y1 signals disappear, leaving the G
signal, the blower motor BLWM will remain on for the
selected blower
−
OFF delay period then switch to con-
tinuous
−
blower speed. When the R
−
to
−
W
−
and
−
Y/Y2,
R
−
to
−
W
−
and
−
Y/Y2
−
and
−
G, R
−
to
−
W
−
and
−
Y1
−
and
−
Y/
Y2, or R
−
to
−
W
−
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 HEAT speed, and begin
a heating cycle. The blower motor BLWM will remain
on until the end of the prepurge period, then shut off for
24 seconds then come back on at HEAT speed. When
the W input signal disappears, the furnace control be-
gins a normal inducer post
−
purge period and the
blower switches to COOL speed after a 3 second
delay. If the R
−
to
−
W
−
and
−
Y/Y2
−
and
−
G or R
−
to
−
W
−
and
−
Y1
−
and
−
Y/Y2
−
and
−
G signals disappear at
the same time, the blower motor BLWM will remain on
for the selected blower
−
OFF delay period. If the R
−
to
−
W
−
and
−
Y/Y2 or R
−
to
−
W
−
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.
Wiring Diagrams
Refer to Figure 25 Figure 55 for wiring diagram.
Troubleshooting
Refer to the service label. (See Figure 51 and Figure 56)