![](/images/new-backgrounds/1055298/5529867x1.webp)
e.Remove blower wheel from housing.
f.Clean wheel and housing.
12.Reassemble motor and blower by reversing steps 11f, finish- ing with 11a. Be sure to reattach ground wire to the blower housing.
13.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 necessary.
14.Spin the blower wheel by hand to verify that the wheel does not rub on the housing.
15.Reinstall blower assembly in furnace.
16.Reinstall control box assembly in furnace.
Heating fan speed(s) MUST be adjusted to provide proper air temperature rise as specified on the rating plate. Failure to adjust the heating speed(s) may shorten heat exchanger life. Recommended operation is at the midpoint of the rise range or slightly above. Refer to ″ SET TEMPERATURE RISE″ under
NOTE: Refer to Table 7 for motor speed lead relocation if leads were not identified before disconnection.
17.Reconnect blower leads to furnace control. Refer to furnace wiring diagram, and connect thermostat leads if previously disconnected. (See Fig. 39.)
18.To check blower for proper rotation: a. Turn on electrical supply.
Blower access door switch opens
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
d.Verify blower is rotating in the correct direction.
19.If furnace is operating properly, RELEASE BLOWER AC- CESS DOOR SWITCH. Replace blower access door and remove any jumpers or reconnect any disconnected thermostat leads.
20.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.
21.Reinstall casing door.
22.Turn on gas supply and cycle furnace through one complete heating and cooling cycle. Verify the unit temperature rise as shown in Adjustments Section. Adjust temperature rise as shown in Adjustments Section. If outdoor temperature is below 70° F, 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 technician:
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
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:
a.Draft safeguard switch.
b.Inducer motor.
c.Pressure switch(es).
d.Limit overtemperature switch.
e.Gas valve.
f.Hot surface igniter.
g.
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 removed from collector box.
7.Disconnect gas line from gas manifold.
8.Remove the 4 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 Fig. 44 and 45 for correct igniter location.
9/32”
11/32”
A02150
Fig. 44—Position of Igniter to Burner
33