All other factory wires can be left connected, but field
thermostat connections may need to be disconnected depend-
ing on their length and routing.
5. Remove 2 screws securing control and transformer support to
furnace.
6. Hang control and transformer support to front of furnace
casing.
7. Remove screws holding blower assembly to blower deck and
slide blower assembly out of furnace.
8. 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.
9. If 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. Remove bolts holding motor mounts to blower housing and
slide motor and mounts out of housing. Disconnect capaci-
tor and ground wire attached to blower housing before
removing motor.
f. Remove blower wheel from housing.
10. Reassemble motor and blower by reversing items 9a through
9f. Be sure to reattach ground wire.
11. Reinstall blower assembly in furnace.
12. Reinstall control and transformer support assembly in furnace.
13. Reconnect blower leads to furnace control and auxiliary limit
switch leads (downflow only).
Refer to furnace wiring diagram, and connect thermostat leads
if previously disconnected. (See Fig. 11.)
NOTE: Refer to Table 3 for motor speed lead relocation if leads
were not identified before disconnection.
Heating speed selection MUST be adjusted to provide proper
temperature rise as specified on the rating plate. Failure to
adjust the heating speed may shorten heat exchanger life.
14. Downflow furnaces only: Reinstall internal vent pipe and
enclosure by reversing items 3a through 3d. NOTE: A
releasing agent such as PAM cooking spray or equivalent
(must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow-Corning 738) are needed before
starting installation. DO NOT substitute any other type of
RTV sealant. G.E. 162 (P771-9003) is available through RCD
in 3-oz tubes.
15. Reinstall vent connector to furnace flue collar. After fully
assembling vent connector to furnace flue collar, securely
fasten vent connector to flue collar with 2 field-supplied,
corrosion-resistant, sheet metal screws located 180 degrees
apart and midway up the collar.
16. Turn on electrical supply. Manually close blower access door
switch. Use a piece of tape to hold switch closed. Check for
proper rotation and speed changes between heating and
cooling by jumpering R to W and then R to Y on furnace
control thermostat terminals.
Blower access door switch opens 115-v power to furnace
control. No component operation can occur. Caution must be
taken when manually closing this switch for service purposes.
Failure to follow this warning could result in electrical shock,
personal injury, or death.
NOTE: If thermostat terminals are jumpered before blower ac-
cess door switch is closed, blower will run for 90 sec before
beginning a heating or cooling cycle.
17. If furnace is operating properly, remove tape to release blower
access door switch, replace blower access door.
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 due to their intricate design. A build-up of soot
and carbon indicates that a problem exists which needs to be
corrected, such as improper adjustment of manifold pressure,
→ Fig. 6—Model 331JAV Downflow
A99092
PRESSURE
SWITCHES
VENT PIPE
ENCLOSURE
CONTROL
FLUE
COLLAR
DRAFT
SAFEGUARD
SWITCH
AUXILIARY
LIMIT
SWITCH
MANUAL
RESET
LIMIT
SWITCHES
RELIEF
BOX
MOUNTING
SCREWS
→ Table 3—Speed Selector
COLOR SPEED
FACTORY
ATTACHED TO
Black High Cool
Yellow (When Present) Medium High Spare
Blue Medium Low Heat
Red Low Spare
White Common Com
Orange (When Present) Medium Spare
4
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