80
440 01 4800 01
Specifications subject to change without notice.
the furnace control CPU will drop the blower motor BLWM
to low--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 seconds at low--cooling air-
flow before transitioning back to continuous--blower air-
flow.
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 op-
erate an additional 90 seconds at high--cooling airflow be-
fore 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 seconds, if no other
function requires blower motor BLWM operation.
6.
Heat pump
See Fig. 39 and 40 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. 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 low--heat 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-
onds 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 blow-
er airflow. If Y/Y2 input is still energized the furnace con-
trol 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 transi-
tion 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 air-
flow 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 blow-
er motor BLWM will operate at continuous blower airflow.
7.
Component self--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. 39.)
Refer to Page 71 for instructions.
