19
Adjust Blower Speed
NOTE: See the Wiring Diagram and Wiring Schematic while
performing the following procedure.
To increase temperature rise:
1. Disconnect power.
2. Remove control box cover.
3. The furnace is factory configured for medium speed (blue
wire) for heating. Connect a lower speed wire (Med/Lo or Lo)
to the Heat terminal.
4. Replace control box cover.
5. Recheck the temperature rise. If the temperature rise cannot
be adjusted within the limits as listed on the furnace rating
plate, see the “Troubleshooting” section.
To decrease temperature rise:
1. Disconnect power.
2. Remove control box cover.
3. The furnace is factory configured for medium speed (blue
wire) for heating. Remove the blue wire from the Heat terminal
and place it at M1 or M2 on the blower control board.
4. Connect a higher blower speed wire (Med/Hi or High) to the
Heat terminal.
5. Replace control box cover.
6. Recheck the temperature rise. If the temperature rise cannot
be adjusted within the limits as listed on the furnace rating
plate, see the “Troubleshooting” section.
NOTE: If low speed (LO) is required for proper temperature
rise, the continuous fan feature should not be used.
Shut Down the Furnace
1. Set the room thermostat to the lowest setting.
2. Disconnect power.
3. Shut off the gas by moving the gas control switch to the OFF
position.
Sequence of Operation
Heating
A call for heat from the thermostat closes R to W on the blower
control board, which begins the ignition sequence. The induced
draft blower output energizes. The pressure switch senses
normal combustion airflow, and closes. After a 15-second pre-
purge, the control energizes the hot surface igniter. After an
igniter warm-up period, the main gas valve energizes. Upon main
burner ignition, the circulating air blower energizes following a
30-second delay.
When the call for heat is satisfied, R to W opens and the gas to
the burners shuts off. The control turns off the inducer after a 5-
second post-purge delay and the heating speed blower output
turns off following the blower “off” delay.
In the event the limit control senses an abnormally high
temperature and opens, the ignition control de-energizes, and the
combustion blower and circulating air blower heating speed
continue to energize.
Fan On
A call for fan from the thermostat closes R to G on the control
board. The control waits for a 1-second thermostat debounce
delay before responding by energizing the heat speed blower.
When the call for fan is turned off, the control de-energizes the
heating speed blower after a 60-second delay.
Cooling
A call for cooling from the thermostat closes R to Y and R to G on
the blower control board. The control waits for a 1-second
thermostat debounce delay before energizing the cool speed
blower. When the call for cooling is satisfied, the control
de-energizes the cooling speed blower after a 60-second delay.
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
