440 04 6001 00
17
Specifications subject to change without notice.
8. Reassemble motor and blower wheel by reversing
items 7b through 7f. Ensure wheel is positioned for
proper rotation.
9. Torque motor mounting bolts to 40 +/
−
10 lb
−
in. when
reassembling.
10. Torque blower wheel set screw to 160 +/
−
20 lb
−
in.
when reassembling.
11. Verify that blower wheel is centered in blower housing
and set screw contacts the flat portion of the motor
shaft. Loosen set screw on blower wheel and
reposition if necessary.
12. Spin the blower wheel by hand to verify that the wheel
does not rub on the housing.
13. Reinstall blower assembly in furnace.
14. Reinstall 2 screws securing blower assembly to
blower deck.
15. Reconnect blower leads to furnace control. Refer to
furnace wiring diagram, and connect thermostat leads
if previously disconnected.
NOTE
: Be sure to attach ground wire and reconnect blower
harness plugs to blower motor.
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Blower door switch opens 115
−
v power to control. No
component operation can occur unless switch is closed.
Caution must be taken when manually closing this
switch for service purposes.
!
WARNING
16. Downflow or horizontal furnaces with vent pipe
through furnace only:
a. Install and connect short piece of vent pipe inside
furnace to existing vent.
b. Connect vent connector to vent elbow.
17. Turn on electrical supply. Manually close blower door
switch. Use a piece of tape to hold switch closed.
Check for proper rotation and speed changes
between heating and cooling by jumpering R to G and
R to Y/Y2 on furnace control thermostat terminals. If
outdoor temperature is below 70
_
F (21
_
C), turn off
circuit breaker to outdoor unit before running furnace
in the cooling cycle. Turn outdoor circuit breaker on
after completing cooling cycle. (See Figure 2.)
NOTE
: If R
−
W/W1 thermostat terminals are jumpered at the
time blower door switch is closed, blower will run for 90 sec
before beginning a heating cycle.
a. Perform component self
−
test as shown at the bottom
of the SERVICE label, located on the control door.
b. Verify blower is rotating in the correct direction
18. If furnace is operating properly, RELEASE BLOWER
DOOR SWITCH. Remove any jumpers or reconnect
any disconnected thermostat leads. Replace blower
door.
19. Turn on gas supply and cycle furnace through one
complete heating cycle. Verify the furnace
temperature rise as shown in Adjustments Section.
Adjust temperature rise as shown in Adjustments
Section.
Cleaning Burners and Flame Sensor
The following items must be performed by a qualified
service technician. If the burners develop an accumulation
of light dirt or dust, they may be cleaned by using the
following procedure:
NOTE
: Use a back-up wrench on the gas valve to prevent
the valve from rotating on the manifold or damaging the
mounting to the burner assembly.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Turn off the gas and electrical supplies to the furnace
and install lockout tag before performing any
maintenance or service. Follow the operating
instructions on the label attached to the furnace.
!
WARNING
1. Disconnect power at external disconnect, fuse or
circuit breaker.
2. Turn off gas at external shut-off or gas meter.
3. Remove control door and set aside.
4. Turn electric switch on gas valve to OFF.
5. Disconnect the gas pipe from gas valve and remove
pipe from the furnace casing.
6. Remove individual wires from terminals on gas valve.
7. Disconnect Hot Surface Igniter (HSI) wires from HSI.
8. Disconnect Flame Sensor wire from Flame Sensor.
9. Support the manifold and remove the 4 screws that
secure the manifold assembly to the burner assembly
and set aside. Note the location of the green/yellow
wire and ground terminal.
10. Inspect the orifices in the manifold assembly for
blockages or obstructions. Remove orifice and clean
or replace orifice.
11. Remove the four screws that attach the top plate of
the casing to the furnace.
12. Raise top plate up slightly and prop it up with a small
piece of wood or folded cardboard.
13. Support the burner assembly and remove the screws
that attach the burner assembly to the heat
exchanger cell panel.
14. Remove wires from both rollout switches.
15. Slide one--piece burner out of slots on sides of burner
assembly.
16. Remove the flame sensor from the burner assembly.
17. (Optional) Remove the Hot Surface Igniter (HSI) and
bracket from the burner assembly.
18. Check igniter resistance. Nominal resistance is 40 to
70 ohms at room temperature and is stable over the
life of the igniter.
19. Clean burner with a brush and a vacuum.
20. Clean the flame sensor with fine steel wool (0000
grade). Do not use sand paper or emery cloth.
To reinstall burner assembly:
1. Install the Hot Surface Igniter (HSI) and bracket in
burner assembly.
2. Install flame sensor on burner.
3. Align the edges of the one-piece burner with the slots
in the burner assembly and slide the burners forward
until they are fully seated in the burner assembly.
4. Align the orifices in the manifold assembly with the
support rings on the end of the burner.
5. Insert the orifices in the support rings of the burners.
