f. Slide filter into cabinet.
g. Replace filter cabinet door.
h. Turn on electrical supply to furnace.
II. BLOWER MOTOR AND WHEEL
The following steps should be performed by a qualified service
technician.
To ensure long life and high efficiency, clean accumulated dirt and
grease from blower wheel and motor annually.
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 2 screws from outer door and then remove outer
door.
3. Vent pipe through furnace casing installation only. For
downflow or horizontal furnaces having vent pipes within
the furnace that pass in from of the blower door:
a. Disconnect vent connector from furnace vent elbow.
b. Disconnect and remove short piece of vent pipe from
within furnace.
4. Remove 2 screws from blower door and remove blower
door.
5. Disconnect blower leads from furnace control. Notice wire
color and location for reassembly.
All other factory wires can be left connected, but field
thermostat connections may need to be disconnected de-
pending on their length and routing.
6. Remove 2 screws securing control and transformer support
to furnace panel.
7. Hang control and transformer support to front of furnace
casing and away from blower compartment.
8. Remove 2 screws holding blower assembly to blower deck
and slide blower assembly out of furnace.
9. Clean blower wheel and motor using a vacuum with soft
brush attachment. Do not remove or disturb balance weights
(clips) on blower wheel blades. The blower wheel should
not be dropped or bent as balance will be affected.
10. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:
a. Mark blower wheel location on shaft before disassembly
to ensure proper reassembly.
b. Loosen setscrew holding blower wheel on motor shaft.
NOTE:
Mark blower mounting arms, motor, and blower housing
so motor and each arm is positioned at the same location during
reassembly.
c. Mark blower wheel orientation and cutoff plate location
to ensure proper reassembly.
d. Remove screws securing cutoff plate and remove cutoff
plate from housing.
e. Disconnect capacitor and ground wire attached to blower
housing before removing motor.
f. Remove bolts holding motor and motor mounts to blower
housing and slide motor and mounts out of housing.
Motor mount belly band need not be removed unless
motor is to be replaced.
Fig. 3—Model 312AAV Upflow
A00342
OUTER DOOR
MOUNTING SCREWS
VENT ELBOW
RATING PLATE
DRAFT
SAFEGUARD SWITCH
GAS MANIFOLD
GAS BURNER
FLAME SENSOR
BLOWER DOOR
SAFETY SWITCH
BLOWER, MOTOR
AND CAPACITOR
PRESSURE
SWITCH
FLUE
COLLECTOR
BOX
GAS VALVE
MANUAL RESET
LIMIT SWITCHES
HOT SURFACE
IGNITER
CONTROL
MAIN LIMIT SWITCH
—3—
