Carrier 58MCB - Manual (Page 5)

5
1. Turn off electrical supply to furnace.
2. Remove main furnace door and blower access panel.
3. Disconnect wires
All factory wires can be left connected, but field thermostat
connections may need to be disconnected depending on
their length and routing.
4. Remove control box mounting screws, and position control
box, transformer, and door switch assembly to right side of
furnace casing.
5. If condensate trap is located in left-- or right--hand side of
furnace casing, proceed to item 6. Otherwise remove trap
and tubing as described below (See Fig. 5.):
a. Disconnect field drain connection from condensate trap.
b. Disconnect drain and relief port tubes from condensate
trap.
c. Remove condensate trap from blower shelf.
6. Remove screws securing blower assembly to blower shelf
and slide blower assembly out of furnace. Detach ground
wire and disconnect blower motor harness plugs from
blower motor.
NOTE: Blower wheel is fragile. Use care.
7. Clean blower wheel and motor by using a vacuum with soft
brush attachment. Be careful not to disturb balance weights
(clips) on blower wheel vanes. Do not bend wheel or blades
as balance will be affected.
8. 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 and blower housing so each
arm is positioned at the same hole 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
capacitor and ground wire attached to blower housing
before removing motor. Motor mounts need not be
removed from motor.
f. Remove blower wheel from housing.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in noise or furnace
component failure.
The blower wheel should not be dropped or bent as balance
will be affected.
CAUTION
!
g. Clean wheel per instructions on degreaser cleaner. Do
not get degreaser in motor.
9. Reassemble motor and blower wheel by reversing items 8b
through 8f. Ensure wheel is positioned for proper rotation.
Be sure to reattach ground wire. Tighten setscrew to 140 to
160 in--lb torque.
NOTE: Be sure to attach ground wire to blower housing.
10. Reinstall blower assembly in furnace.
11. Reinstall control box, transformer, and door switch as-
sembly on blower shelf.
12. Reinstall condensate trap and tubing if previously removed.
a. Reinstall condensate trap in hole in blower shelf.
b. Connect condensate trap drain tubes. See Fig. 5 or
tubing diagram on main furnace door for proper tube
location.
NOTE: Ensure tubes are not kinked or pinched, as this will affect
operation.
(1.) Connect one tube (blue or blue and white striped)
from collector box.
(2.) Connect one tube (violet or unmarked) from in-
ducer housing.
(3.) Connect one tube (relief port, green or pink) from
collector box.
c. Connect field drain to condensate trap.
NOTE: Ensure tubes are not kinked or pinched, as this will affect
operation.
13. Reinstall control box, transformer, and door switch as-
sembly on blower shelf.
14. Reconnect wires. Refer to furnace wiring diagram and con-
nect thermostat leads if previously disconnected. (See Fig.
21.)
NOTE: Refer to Table 3 for motor speed lead reconnection if
leads were not identified before disconnection.
UNIT DAMAGE HAZARD
Failure to adjust the heating speed may shorten heat
exchanger life.
Heating speed selection MUST be adjusted to provide
proper temperature rise as specified on the rating plate.
CAUTION
!
Table 3 – Speed Selection
COLOR SPEED
FACTORY
ATTACHED TO
Black High Cool
Yellow (When Present) Medium High Spare
Blue Medium Low Heat
Red Low Fan
White Common Com
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Blower access panel 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.
! WARNING
15. Turn on electrical supply. Manually close blower access
panel door switch. Use a piece of tape to hold switch closed.
Check for proper rotation and speed changes between heat-
ing and cooling by jumpering R to G and R to Y/Y2 on
furnace control thermostat terminals. (See Fig. 15.)
16. If furnace is operating properly, release blower access panel
door switch, replace blower access panel, and replace main
furnace door.
58MC
B