Cleaning Burners - Carrier 58MTA Service Manual

2. Remove main furnace door and blower access door.
3. Disconnect blower motor wires from furnace control. Field
thermostat connections may need to be disconnected depend-
ing 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. 8, top left) :
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.
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 capaci-
tor and ground wire attached to blower housing before
removing motor. Motor mounts do not need to be removed
from motor.
f. Remove blower wheel from housing.
The blower wheel should not be dropped or bent as balance
will be affected.
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.
Tighten setscrew to between 140-160 in.-lb torque.
10. Reinstall blower assembly in furnace.
11. Reinstall control box, transformer, and door switch assembly
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. 8 or tubing
diagram on main furnace door for proper tube location.
(1.) Connect 1 tube (blue or blue and white striped) from
collector box.
(2.) Connect 1 tube (violet or unmarked) from inducer
housing.
(3.) Connect 1 tube (relief port, green or pink) from
collector box.
NOTE: Ensure tubes are not kinked or pinched, as this will affect
operation.
c. Connect field drain to condensate trap.
13. Reconnect wires.
Refer to furnace wiring diagram and connect thermostat leads if
previously disconnected. (See Fig. 16.)
NOTE: Refer to Table 1 for motor speed lead reconnection if
leads were not identified before disconnection.
Heating air 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 ex-
changer life.
Table 1—Speed Selection
COLOR SPEED
White Common
Black
Yellow Med-High
Orange†
Blue Med-Low
Red
* Continuous blower speed.
† Available on 5-speed blowers only.
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 personal injury
or death.
14. 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 by performing a component
self-test as shown at the bottom of Service label. (See Fig. 17.)
15. If furnace is operating properly, remove tape to release blower
access door switch, replace blower access door, and replace
main furnace door.
Step 3—Cleaning Burners
The following items should be performed by a qualified service
technician. If the burners develop an accumulation of light dirt or
dust, they may be cleaned by using the following procedure:
1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Remove burner box cover.
4. Using backup wrench, disconnect gas supply pipe from
furnace gas control valve.
Label all wires prior to disconnection when servicing con-
trols. Wiring errors can cause improper and dangerous
operation.
5. Remove wires from gas valve. Note location for reassembly.
4
AS SHIPPED
C
OM
High Cool
SPARE
Med High-Gas Heat
Spare/High-Gas Heat
Low* Low-Gas Heat