Specifications are subject to change without notice.
441 01 3700 00
47
plies to operation with a Thermidistat. 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 drop the blower
airflow to 90 percent of low--cooling airflow which is
the true on--board CF selection as shown in Table 4
and Fig. 47.
b.
High cooling
--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 90 percent of high--cooling airflow. High--
cooling airflow is based on the A/C (air conditioning)
selection shown in Fig. 47.
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
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 at continuous blower
airflow. Continuous blower airflow selection is initially
based on the CF selection shown in Table 4 and and Fig.
47. Factory default is shown in Table 4. Terminal EAC--1
is energized as long as the blower motor BLWM is ener-
gized.
During a call for heat, the furnace control CPU will transi-
tion the blower motor BLWM to continuous blower air-
flow or heat airflow whichever is lowest. The blower mo-
tor BLWM will remain ON until the main burners ignite
then shut OFF and remain OFF for the blower--ON delay
(25 seconds in high--heat), allowing the furnace heat ex-
changers to heat up more quickly, then restarts at the end
of the blower--ON delay period at heat.
The blower motor BLWM will revert to continuous--blow-
er airflow after
the high--hea
ting cycle is completed.
When the thermostat “calls for low--cooling”, the blower
motor BLWM will switch to operate at low--cooling air-
flow. When the thermostat is satisfied, the blower motor
BLWM will operate an additional 90 seconds at low--cool-
ing airflow before transitioning back to continuous--blow-
er airflow.
When the thermostat “calls for high--cooling”, the blower
motor BLWM will operate at 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 sec-
onds, if no other function requires blower motor BLWM
operation.
Continuous Blower Speed Selection from Thermostat
To select different continuous--blower airflow 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 the continuous--blower airflow from the
factory setting to the next highest CF selection airflow as
shown in Table 4 and Fig. 47. Momentarily turning off the
FAN switch again at the thermostat will shift the continu-
ous--blower airflow up one more increment. If you repeat
this procedure enough you will eventually shift the contin-
uous--blower airflow to the lowest CF selection as shown
in Table 4 and Fig. 47. 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).
5.
Heat pump
See Fig. 27 for thermostat connections.
When installed with a heat pump, the furnace control auto-
matically changes the timing sequence to avoid long blow-
er off times during demand defrost cycles. Whenever
W/W1 is energized along with Y1 or Y/Y2, the furnace
control CPU will transition to or bring on the blower mo-
tor BLWM at cooling airflow or low--heat airflow, which-
ever is lowest. The blower motor BLWM will remain on
until the main burners ignite then shut OFF and remain
OFF for 25 seconds before coming back on at heating air-
flow. When the W/W1 input signal disappears, the furnace
control begins a normal inducer post--purge period while
changing the blower airflow. If Y/Y2 input is still ener-
gized the furnace control CPU will transition the blower
motor BLWM airflow to cooling airflow. If Y/Y2 input
signal disappears and the Y1 input is still energized the
furnace control CPU will transition the blower motor
BLWM to low--cooling airflow. If both the Y1 and Y/Y2
signals disappear at the same time, the blower motor
BLWM will remain on at low--heat airflow for the selected
blower--OFF delay period. At the end of the blower-- OFF
delay, the blower motor BLWM will shut OFF unless G is
still energized, in which case the blower motor BLWM
will operate at continuous blower airflow.
6.
Component test
The furnace features a component test system to help diag-
nose a system problem in the case of a component failure.
To initiate the component test procedure, ensure that there
are no thermostat inputs to the control and all time delays
have expired. Turn on setup switch SW1--6. (See Fig. 46.)
NOTE
: The component test feature will not operate if the control
is receiving any thermostat signals or until all time delays have
expired.
The component test sequence is as follows:
a. The furnace control CPU turns the inducer motor ON
and keeps it ON through step c.
b. After waiting 10 seconds the furnace control CPU
turns the hot surface igniter ON for 15 seconds, then
OFF.
c. The furnace control CPU then turns the blower motor
BLWM on at 50 percent torque for 15 seconds, then
OFF.
NOTE
: The EAC terminals are energized when the blower is
operating.
After the component test is completed, status code
heartbeat, 2+5
will flash. See component test section or Service Label (Fig. 45)
for explanation of status codes.
NOTE
: To repeat component test, turn setup switch SW1--6 to
OFF and then back ON.
Wiring Diagrams
Refer to Fig. 48 for wiring diagram.
Troubleshooting
Refer to the service label. (See Fig. 45) The Troubleshooting
Guide (See Fig. 52) can be a useful tool in isolating furnace
operation problems. Beginning with the word “Start,” answer
each question and follow the appropriate arrow to the next item.
The Guide will help to identify the problem or failed component.
After replacing any component, verify correct operation
sequence.
