Flame Sensor Cleaning - Carrier 58SU0A Series Installation, Start-Up, Operating And Service And Maintenance Instructions

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 outer door.
3. Remove two screws from blower access door and remove
blower access door.
4. All factory wires can be left connected, but field thermo-
stat connections may need to be disconnected depending
on their length and routing.
5. Remove two screws holding blower assembly to blower
deck and slide blower assembly out of furnace.
6. Clean blower wheel and motor using a vacuum with soft
brush attachment. Blower wheel blades may be cleaned
with a small paint or flux brush. Do not remove or disturb
balance weights (clips) on blower wheel blades.
7. Vacuum any loose dust from blower housing, wheel and
motor.
8. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an appro-
priate degreaser. To remove wheel:
NOTE: Before disassembly, mark blower motor, and blower
housing so motor and each arm is positioned at the same location
during reassembly.
9. Reassemble motor and blower by reversing steps 9d
finishing with 9a. Be sure to reattach ground wire to the
blower housing.
a. Disconnect power choke wires (if used) and ground wire
attached to blower housing.
b. Remove screws securing cutoff plate and remove cutoff
plate from housing.
c. Loosen set screw holding blower wheel on motor shaft
(160+/- -20 in.- -lb. when reassembling).
d. Remove bolts holding motor to blower housing and slide
motor out of wheel (40+/- -10 in.- -lb. when reassembling).
e. Remove blower wheel from housing.
f. Clean wheel and housing.
10. 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 neces-
sary.
11. Spin the blower wheel by hand to verify that the wheel
does not rub on the housing.
12. Reinstall blower assembly in furnace.
13. Reinstall two screws securing blower assembly to blower
deck.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in shortened heat
exchanger life.
Heating fan speed(s) MUST be adjusted to provide proper
air temperature rise as specified on the rating plate.
Recommended operation is at the midpoint of the rise range
or slightly above. Refer to "SET TEMPERATURE RISE"
under START- -UP, ADJUSTMENT,
CHECK.
NOTE: Refer to Table 5 for motor speed lead relocation if leads
were not identified before disconnection.
FLAME SENSOR CLEANING AND SERVICING
IGNITOR
Cleaning Flame Sensor
The following items must be performed by a qualified service
technician. If the flame sensor develops an accumulation of light
dirt or dust, it may be cleaned by using the following procedure:
Refer to Fig. 36.
and SAFETY
33
14. Refer to furnace wiring diagram, and connect thermostat
leads if previously disconnected.
15. To check blower for proper rotation:
a. Turn on electrical supply.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115- -v power to
furnace control. No component operation can occur
unless switch is closed. Exercise caution to avoid
electrical shock from exposed electrical components
when manually closing this switch for service purposes.
b. Manually close blower access door switch.
c. Verify blower is rotating in the correct direction.
16. If furnace is operating properly, RELEASE BLOWER
ACCESS DOOR SWITCH. Remove any jumpers or
reconnect any disconnected thermostat leads. Replace
blower access door.
17. Reinstall outer door.
18. Cycle furnace through one complete heating and cooling
cycle. Verify the furnace temperature rise as shown in
"Adjustments" Section. Adjust temperature rise as shown
in "Adjustments" Section. If outdoor temperature is below
70_F, (21_C) turn off circuit breaker to outdoor unit be-
fore running furnace in the cooling cycle. Turn outdoor
circuit breaker on after completing cooling cycle.
WARNING
!
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Turn off the gas and electrical supplies to the furnace and
install lockout tag before performing any maintenance or
service. Follow the operating instructions on the label
attached to the furnace.
1. Disconnect power at external disconnect, fuse or circuit
breaker.
2. Turn off gas at external shut-off or gas meter.
3. Remove control door and set aside.
4. Turn electric switch on gas valve to OFF.
5. Disconnect Flame Sensor wire from Flame Sensor.
6. Remove the flame sensor from the burner assembly.
7. (Optional) Remove the Hot Surface Igniter (HSI) and
bracket from the burner assembly.
8. Check igniter resistance. Nominal resistance is 40 to 70
ohms at room temperature and is stable over the life of the
igniter.