59CU5A: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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b. When the R-to-Y/Y2 circuit is closed, R-to-G circuit is open, and
there is a demand for dehumidification, the furnace blower motor
BLWM will drop the blower airflow to 65 percent of
high-cooling airflow for a maximum of 10 minutes each cooling
cycle or until the R-to-G circuit closes or the demand for
dehumidification is satisfied. High-cooling airflow is based on
the A/C (air conditioning) selection shown in
.
c. 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 at continuous blower airflow.
Continuous blower airflow selection is initially based on the CF
(continuous fan) selection shown in
. Factory default is
shown in
. Terminal EAC-1 is energized as long as the
blower motor BLWM is energized.
During a call for heat, the furnace control CPU will transition the
blower motor BLWM to continuous blower airflow or the
mid-range airflow, whichever is lowest. The blower motor BLWM
will remain ON until the main burners ignite then shut OFF and
remain OFF for the blower-ON delay (25 sec in heat), allowing the
furnace heat exchangers to heat up more quickly, then restarts at the
end of the blower-ON delay period at heat airflow..
The blower motor BLWM will revert to continuous-blower airflow
after the heating cycle is completed. In heat the furnace control
CPU will drop the blower motor BLWM to heat airflow during the
selected blower-OFF delay period before transitioning to
continuous-blower airflow.
When the thermostat “calls for low-cooling”, the blower motor
BLWM will switch to operate at low-cooling airflow. When the
thermostat is satisfied, the blower motor BLWM will operate an
additional 90 sec at low-cooling airflow before transitioning back to
continuous-blower 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 sec
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, 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 sec 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
. Momentarily turning off the FAN switch again at
the thermostat will shift the continuous-blower airflow up one more
increment. If you repeat this procedure enough you will eventually
shift the continuous-blower airflow to the lowest CF selection as
shown in
. 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
and thermostat wiring for connections.
When installed with a heat pump, the furnace control automatically
changes the timing sequence to avoid long blower 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 motor BLWM at cooling airflow or the mid-range
airflow, whichever is lowest. The blower motor BLWM will remain
on until the main burners ignite then shut OFF and remain OFF for
25 sec before coming back on at heating airflow. 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 energized 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 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.
Component Self-Test
Refer to “Component Self Test” in the Service and Maintenance section
for details.
Wiring Diagrams
Refer to
Troubleshooting
Refer to the service label, see
, wiring diagram, see
, and
the Service Guide (Page 52) can be a useful tool in isolating furnace
operation problems. The Guide will help to identify the problem or
failed component. After replacing any component, verify correct
operation sequence.