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935CA: Installation, Start-up, Operating and Service and Maintenance Instructions
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
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
shown in
Fig.
65. 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
Fig.
65. 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. 42
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
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
before
transitioning
back
the blower motor BLWM at cooling airflow or the mid-range
airflow, whichever is lowest. The blower motor BLWM will remain
to
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
Fig. 76
for wiring diagram.
Troubleshooting
Refer to the service label, see
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.
62
Fig.
70, wiring diagram, see
Fig.
76, and
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