Carrier 59MN7B Installation, Start-Up, Operating And Service And Maintenance Instructions page 82

7. Replace filter cabinet door.
8. Turn on electrical supply to furnace.
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 depend-
ing 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 Fig. 66 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 re-
assembling.
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 neces-
sary.
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.
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