Electrical Shock Hazard; Cleaning Heat Exchanger - Kenmore N8MSL0701412A1 Installation Instructions Manual

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 ap-
propriate degreaser. To remove wheel:
NOTE: Before disassembly, mark blower motor, and blower
housing so motor and each arm is positioned at the same
location during reassembly.
a. Disconnect capacitor wires and ground wire at-
tached 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.-Ib, when reassembling).
d. Remove bolts holding motor to blower housing and
slide motor out of wheel (40+/-10 in.-Ib, when reas-
sembling).
e. Remove blower wheel from housing.
f. Clean wheel and housing.
10. Reassemble motor and blower by reversing steps 9f
through 9a, finishing with 9a. 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 reposi-
tion 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.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in shortened heat
exchanger life.
Heating fan speed(s) MUST be adjusted to provide
proper air temperature rise as specified on the rating
plate. Recommended operation is at the midpoint of the
rise range or slightly above. Refer to SET
TEMPERATURE RISE under START-UP,
ADJUSTMENT, and SAFETY CHECK.
14. Connect thermostat leads if previously disconnected.
15. To check blower for proper rotation:
a. Turn on electrical supply.
ELECTRICALSHOCKHAZARD
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.
b. Manually close blower access door switch.
NOTE: If thermostat terminals are jumpered at the time
blower access door switch is closed, blower wilt run for 90
sec before beginning a heating or cooling cycle.
c. Perform component self-test as shown on the
SERVICE label, located on the blower access door.
441 01 1402 02
16. If furnace is operating properly, RELEASE BLOWER
ACCESS DOOR SWITCH. Remove any jumpers or re-
connect any disconnected thermostat leads. Replace
blower access door.
17. 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.
18. Reinstall casing door.
19. Turn on gas supply and cycle furnace through one
complete heating and cooling cycle. Verify the furnace
temperature rise as shown in Adjustments Section. Ad-
just temperature rise as shown in Adjustments Section.
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.
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 heavy 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.
If it becomes necessary to clean the heat exchangers
because of dust or corrosion, proceed as follows:
1. Turn OFF gas and electrical power to furnace.
2. Remove outer access door.
3. Disconnect vent connector from furnace vent elbow.
4. For downflow or horizontal furnace having an internal
vent pipe, remove internal vent pipe within the casing.
5. Disconnect wires to the following components. Mark
wires to aid in reconnection of (be careful when discon-
necting wires from switches because damage may oc-
cur):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switch(es).
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switches.
i. Remove NOx baffles on low NOx models.
6. Remove screws that fasten the collector box assembly
to the cell panel. Be careful not to damage the collector
box. Inducer assembly and elbow need not be re-
moved from collector box.
7. Disconnect gas line from gas manifold.
8. Remove the 5 screws that attach the burner assembly
to the cell panel. The gas valve and individual burners
need not be removed from support assembly.
NOTE: Be very careful when removing burner assembly to
avoid breaking igniter. See Figure 45 and Figure 46 for
correct igniter location.
9. Using field-provided 25-caliber rifle cleaning brush,
36-in. (914 mm) long, 1/4 in. (6 mm) diameter steel
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