53
BLOWER MOTOR AND WHEEL
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Blower access 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
NOTE: The blower wheel should not be dropped or bent as
balance will be affected.
The following steps should be performed by a qualified
service agency.
To ensure long life 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.
Clean blower motor and wheel as follows:
1. Turn off electrical supply to furnace.
2. Loosen the thumbscrew on outer door and then remove
outer door.
3. For downflow or horizontal furnaces having vent pipes
within the furnace that pass in front of the blower access
door:
a. Disconnect vent connector from furnace vent elbow.
b. Disconnect and remove short piece of vent pipe from
within furnace.
4. Remove 2 screws from blower access door and remove
blower access door.
5. Disconnect blower leads from furnace control. Record
wire color and location for reassembly. All other factory
wires can be left connected, but field thermostat
connections may need to be disconnected depending on
their length and routing.
6. Remove 2 screws holding control box to blower shelf.
7. Hang control box from front of furnace casing and away
from blower compartment.
8. Remove 2 screws holding blower assembly to blower
deck and slide blower assembly out of furnace.
9. Clean blower wheel and motor using a vacuum with soft
brush attachment. Blower wheel blades may be cleaned
with a small paint or flux brush. Do not remove or disturb
balance weights (clips) on blower wheel blades.
10. Vacuum any loose dust from blower housing, wheel and
motor.
11. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:
NOTE: Before disassembly, mark blower mounting arms, motor,
and blower housing so motor and each arm is positioned at the
same location during reassembly.
a. Disconnect ground wire attached to blower housing.
b. Remove screws securing cutoff plate and remove
cutoff plate from housing.
c. Loosen set screw holding blower wheel on motor shaft
(160+/--20 in.-- lb. when assembling).
d. Remove bolts holding motor to blower housing and
slide motor out of wheel (40+/-- 10 in.-- lb. when
reassembling).
e. Remove blower wheel from housing.
f. Clean wheel and housing.
12. Reassemble motor and blower by reversing steps 11e,
through 11a. Be sure to reattach ground wire to the blower
housing.
13. 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.
14. Spin the blower wheel by hand to verify that the wheel
does not rub on the housing.
15. Reinstall blower assembly in furnace.
16. Reinstall control box assembly in furnace.
NOTE: Refer to Fig. 59 if leads were not identified before
disconnection.
17. Reconnect blower leads to furnace control. Refer to
furnace wiring diagram, and connect thermostat leads if
previously disconnected.
18. To check blower for proper rotation:
a. Turn on electrical supply.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115--v power to furnace
control. No component operation can occur unless switch is
closed. Exercise caution to avoid electrical shock from
exposed electrical components when manually closing this
switch for service purposes.
!
WARNING
b. Manually close blower access door switch.
NOTE: If R--W/W1 thermostat terminals are jumpered at the
time blower access door switch is closed, blower will run for 90
sec before beginning a heating cycle.
c. Perform component self-- test as shown at the bottom
of the SERVICE label, located on th e front of blower
access door.
d. Verify blower is rotating in the correct direction
19. If furnace is operating properly, RELEASE BLOWER
ACCESS DOOR SWITCH. Remove any jumpers or
reconnect any disconnected thermostat leads. Replace
blower access door.
20. 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.
21. Turn on gas supply and cycle furnace through one
complete heating and cooling cycle. Verify the furnace
temperature rise as shown in Adjustments Section. Adjust
temperature rise as shown in Adjustments Section. If
outdoor temperature is below 70_F, turn off circuit breaker
to outdoor unit before running furnace in the cooling
cycle. Turn outdoor circuit breaker on after completing
cooling cycle.
CLEANING HEAT EXCHANGER
The following steps should be performed by a qualified
service agency:
NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, they should be replaced rather than trying to clean
them thoroughly. A build--up of soot and carbon indicates that a
315A
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