48
Table 13 – Filter Size Information -- In. (mm)
FURNACE CASING WIDTH
FILTER SIZE
FILTER TYPE
SIDE
RETURN
BOTTOM
RETURN
14---1/2 (368)
16 X 25 X 3/4
(406 X 635 X 19)
14 X 25 X 3/4
(356 X 635 X 19)
Washable*
17---1/2 (445)
16 X 25 X 3/4
(406 X 635 X 19)
16 X 25 X 3/4
(406 X 635 X 19)
Washable*
21 (533)
16 X 25 X 3/4
(406 X 635 X 19)
20 X 25 X 3/4
(508 X 635 X 19)
Washable*
24 (610)
16 X 25 X 3/4
(406 X 635 X 19)
24 X 25 X 3/4
(610 X 635 X 19)
Washable*
* Recommended
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. 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 screws from blower access door and remove
blower access door.
5. All factory wires can be left connected, but field thermo-
stat connections may need to be disconnected depending
on their length and routing.
6. Remove 2 screws holding blower assembly to blower
deck and slide blower assembly out of furnace.
7. 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.
8. Vacuum any loose dust from blower housing, wheel and
motor.
9. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an appro-
priate 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 reas-
sembling).
e. Remove blower wheel from housing.
f. Clean wheel and housing.
10. Reassemble motor and blower by reversing steps 9a,
through 9e. Be sure to reattach ground wire to the blower
housing.
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 fur-
nace wiring diagram, and connect thermostat leads if pre-
viously disconnected.
16. 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 the front of blower
access door.
d. Verify blower is rotating in the correct direction
17. If furnace is operating properly, RELEASE BLOWER
ACCESS DOOR SWITCH. Remove any jumpers or re-
connect any disconnected thermostat leads. Replace
blower access door.
18. Downflow or horizontal furnaces with vent pipe through
furnace only:
a. Install and connect short piece of vent pipe inside fur-
nace to existing vent.
b. Connect vent connector to vent elbow.
19. Reinstall outer door.
20. Turn on gas supply and cycle furnace through one com-
plete heating and cooling cycle. Verify the furnace temper-
ature rise as shown in Adjustments Section. Adjust tem-
perature rise as shown in Adjustments Section. If outdoor
temperature is below 70
_
F, turn off circuit breaker to out-
door 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
problem exists which needs to be corrected, such as improper
adjustment of manifold pressure, insufficient or poor quality
combustion air, incorrect size or damaged manifold orifice(s),
improper gas, or a restricted heat exchanger. Action must be taken
to correct the problem.
314AA
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