8. Vacuum any loose dust from blower housing, wheel
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:
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
in.-Ib, when reassembling).
d. Remove bolts holding motor to blower housing and
slide motor out of wheel (40+/-10 in.-Ib, when reas-
e. Remove blower wheel from housing.
f. Clean wheel and housing.
motor and blower by reversing steps 9f
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
proper air temperature
rise as specified
on the rating
operation is at the midpoint of the
and SAFETY CHECK.
14. Connect thermostat leads if previously disconnected.
15. To check blower for proper rotation:
a. Turn on electrical supply.
Failure to follow this warning could result in personal
injury, or death.
shock from exposed
when manually closing this switch for service purposes.
b. Manually close blower access door switch.
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
ACCESS DOOR SWITCH. Remove any jumpers or re-
connect any disconnected
blower access door.
17. Downflow or horizontal furnaces with vent pipe through
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
complete heating and cooling cycle. Verify the furnace
temperature rise as shown in Adjustments
rise as shown in Adjustments
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
by a qualified
If the heat exchangers
get a heavy accumulation
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,
insufficient or poor quality combustion
air, incorrect size or
gas, or a restricted
heat exchanger. Action must be taken to correct the problem.
If it becomes
to clean the
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.
wires to the following
wires to aid in reconnection of (be careful when discon-
necting wires from switches because damage may oc-
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switch(es).
d. Limit overtemperature
e. Gas valve.
f. Hot surface igniter.
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.
Be very careful when removing burner assembly to
See Figure 45 and
Figure 46 for
correct igniter location.
9. Using field-provided
(914 mm) long, 1/4 in. (6 mm) diameter steel