International comfort products N8MXL Installation Instructions Manual page 41

10. Reassemble motor and blower by reversing steps 11f
through 11a, finishing with 11a. 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.
14. Reinstall two screws securing blower assembly to
blower deck.
CAUTION
!
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"
ADJUSTMENT, and SAFETY CHECK.
NOTE: Refer to Table 5 for motor speed lead relocation if
leads were not identified before disconnection.
15. Refer to furnace wiring diagram, and connect thermo-
stat leads if previously disconnected.
16. To check blower for proper rotation:
a. Turn on electrical supply.
WARNING
!
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.
b. Manually close blower access door switch.
NOTE: If thermostat terminals are jumpered at the time
blower access door switch is closed, blower will run for 90
sec before beginning a heating or cooling cycle.
c. Perform component self−test as shown at the bottom
of the SERVICE label, located on the 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.
441 01 1421 01
under START−UP,
Specifications are subject to change without notice.
20. Cycle furnace through one complete heating and cool-
ing 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, (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
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.
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. Remove
NOx baffles if installed.
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" (6 mm) diameter steel
spring cable, a variable speed reversible electric drill,
and vacuum cleaner, clean cells as follows:
a. Remove metal screw fitting from wire brush to allow
insertion into cable.
b. Insert the twisted wire end of brush into end of spring
cable, and crimp tight with crimping tool or crimp by
striking with ball−peen hammer. TIGHTNESS IS
VERY IMPORTANT.
of manifold pressure,
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