ICP F9MVE0401410A, Service And Technical Support Manual

SERVICE AND TECHNICAL SUPPORT MANUAL

Gas Furnace: (F/G)9MVE

Specifications  subject to change without notice.

440 04 4800 00

32

low

−

heat or high

−

heat airflow, respectively. 

The blower motor BLWM will revert to continuous

−

blower

airflow after the heating cycle is completed. In high

−

heat,

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 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 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

seconds, if no other function requires blower motor

BLWM operation.

6.

Heat pump

See 

Figure 20

 and 

Figure 21

 for thermostat

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,

low

−

heat 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 seconds 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 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.

Component Self Test

Refer to page 18 for instructions.

Figure 18

Variable Speed Furnace with Single
Stage Air Conditioner

NOTE

9

Figure 19

Variable Speed Furnace with

Two

−

Stage Air Conditioner

L09F027

NOTE

9