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a. Remove dust caps or plugs from oil ports located at each
end of motor.
b. Use a good grade of SAE 20 nondetergent motor oil and
put 1 teaspoon, 5 cc, 3/16 oz, or 16 to 25 drops in each
oil port. Do not over-oil.
c. Allow time for total quantity of oil to be absorbed by
each bearing.
d. Wipe excess oil from motor housing.
e. Replace dust caps or plugs on oil ports.
12. Remove blower wheel from housing.
a. Mark cutoff location to ensure proper reassembly.
b. Remove screws holding cutoff plate and remove cutoff
plate from housing.
c. Lift blower wheel from housing through opening.
13. Clean blower wheel and motor using a vacuum cleaner with
soft brush attachment. Do not remove or disturb balance
weights (clips) on blower wheel blades. The blower wheel
should not be dropped or bent as balance will be affected.
14. Reinstall blower wheel by reversing items 12 a through c.
Be sure wheel is positioned for proper rotation.
15. Reassemble motor and blower by reversing items 5 through
10. If motor has ground wire, be sure it is connected as
before.
CAUTION: Be sure the motor is properly positioned in
the blower housing. The motor oil ports must be at a
minimum of 45° above the horizontal centerline of the
motor after the blower assembly has been reinstalled in
the furnace.
16. Reinstall blower assembly in furnace.
17. Reinstall control. Connect blower electrical leads to control.
Please note that the common wire connection is 3/16 in. and
all other wire connections are 1/4 in. for assembly. DO
NOT FORCE.
18. Reconnect wires to auxiliary limit switch on blower housing
(downflow/horizontal furnace only).
19. Reinstall vent pipe and enclosure (downflow/horizontal
furnace only).
20. Turn on electrical power and check for proper rotation and
speed changes between heating and cooling.
21. Replace blower access door. Secure with screw (when used
on downflow/horizontal furnace only).
C. Cleaning Heat Exchanger
The following steps should be performed by a qualified service
technician.
NOTE: Deposits of soot and carbon indicate the existence of a
problem which needs to be corrected. Take action to correct the
problem.
If it becomes necessary to clean the heat exchanger because of
carbon deposits, soot, etc., proceed as follows:
1. Turn off gas and electrical power to furnace.
2. Remove screw from front of blower access door
(downflow/horizontal furnace only) and remove control and
blower access doors.
3. Remove vent pipe enclosure (downflow/horizontal furnace
only) and disconnect vent pipe from relief box.
4. Remove 2 screws that secure relief box. (See Fig. 6 or 7.)
5. Disconnect wires to the following components.
a. Blocked vent safeguard
b. Inducer motor
c. Pressure switch
d. Limit overtemperature switch(es)
e. Gas valve
f. Hot surface ignitor
g. Flame-sensing electrode
6. Remove 8 screws that secure flue collector box to center
panel. Be careful not to damage sealant.
7. Remove complete inducer assembly from furnace, exposing
flue openings.
8. Clean cells using field-provided small wire brush, steel
spring cable, reversible electric drill, and vacuum cleaner.
a. Assemble wire brush and steel spring cable.
(1.) Use 48 in. of 1/4-in. diameter high-grade steel
spring cable (commonly known as drain clean-out
or Roto-Rooter cable).
→ Fig. 6—Model 383KAV Upflow
A98528
C
OM
24V
HUM
GRYW
BLOCKED
VENT
SAFEGUARD
FLUE
COLLECTOR
BOX
MOUNTING
SCREWS
RELIEF
BOX
CONTROL
FILTER
RETAINER
WASHABLE
FILTER
→ Fig. 7—Model 373LAV Downflow
A98529
VENT PIPE
ENCLOSURE
BLOCKED
VENT
SAFEGUARD
MANUAL
RESET LIMIT
SWITCHES
AUXILIARY
LIMIT
SWITCH
(WHEN USED)
MOUNTING
SCREWS
RELIEF
BOX
C
OM
24V
HUM
GRYW
CONTROL
BOARD
—4—
→