440 04 6000 00
15
Specifications subject to change without notice.
Blower Motor and Wheel Maintenance
To ensure long life, economy, and high efficiency, clean
accumulated dirt and grease from blower wheel and motor
annually.
The inducer and blower motors are pre
−
lubricated and
require no additional lubrication. These motors can be
identified by the absence of oil ports on each end of the
motor.
The following items should be performed by a qualified
service technician. Clean blower motor and wheel as
follows:
1. Turn off electrical supply to furnace.
2. Remove blower door.
3. All factory wires can be left connected, but field
thermostat and accessory wiring may need to be
disconnected depending on their length and routing.
4. If the vent and combustion air pipe passes through
the blower compartment, it will be necessary to
remove the pipes from the blower compartment.
Disconnect the vent and combustion air pipe by:
a. Loosen the clamps on the vent couplings and
combustion air pipe external to the furnace.
b. Separate the pipes from the couplings and move
them aside.
c. Loosen the clamps on the vent couplings and
combustion air pipe located on the blower shelf.
d. Separate the pipes from the blower compartment
and set aside.
e. Remove the couplings from the pipe adapters and
set aside.
f. After servicing the blower, reverse steps a through
e.
g. Tighten all clamps 15 lb
−
in.
See Figure 13 for steps 5 through 14.
5. Remove screws securing blower assembly to blower
shelf and slide blower assembly out of furnace.
Detach ground wire and disconnect blower motor
harness plugs from blower motor.
NOTE
: Blower wheel is fragile. Use care.
6. Clean blower wheel and motor by using a vacuum
with soft brush attachment. Be careful not to disturb
balance weights (clips) on blower wheel vanes. Do
not bend wheel or blades as balance will be affected.
7. If greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:
a. Mark blower wheel location on shaft before
disassembly to ensure proper reassembly.
b. Loosen setscrew holding blower wheel on motor
shaft.
NOTE
: Mark blower mounting arms and blower housing so
each arm is positioned at the same hole location during
reassembly.
c. Mark blower wheel orientation and cutoff plate
location to ensure proper reassembly.
d. Remove screws securing cutoff plate and remove
cutoff plate from housing.
e. Remove bolts holding motor mounts to blower
housing and slide motor and mounts out of housing.
f. Remove blower wheel from housing.
g. Clean wheel per instructions on degreaser cleaner.
Do not get degreaser in motor.
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
