Bryant 926TC Installation, Start-Up, Operating And Service And Maintenance Instructions page 67

926TC: Installation, Start-up, Operating and Service and Maintenance Instructions
g. Clean wheel per instructions on degreaser cleaner. Do not get
degreaser in motor.
8. Reassemble motor and blower wheel by reversing items 7b through
7f. Ensure wheel is positioned for proper rotation.
9. Torque motor mounting bolts to 40 +/- 10 lb-in. when reassembling.
10. Torque blower wheel set screw to 160 +/- 20 lb-in. when
reassembling.
11. 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 necessary.
12. Spin the blower wheel by hand to verify that the wheel does not rub
on the housing.
13. Reinstall blower assembly in furnace.
NOTE: On 66100V21, ensure that the blower wrapper sits on top of the
two tabs on blower sidewalls. (See
14. Reinstall 2 screws securing blower assembly to blower deck.
15. Reconnect blower leads to furnace control. Refer to furnace wiring
diagram, and connect thermostat leads if previously disconnected.
NOTE: Be sure to attach ground wire and reconnect blower harness
plugs to blower motor.
WARNING
!
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury or death.
Blower door switch opens 115-V power to control. No component
operation can occur unless switch is closed. Caution must be taken
when manually closing this switch for service purposes.
16. Downflow or horizontal furnaces with vent pipe through furnace
only:
a. Install and connect short piece of vent pipe inside furnace to
existing vent.
b. Connect vent connector to vent elbow.
17. Turn on electrical supply. Manually close blower door switch.
Check for proper rotation and speed changes between heating and
cooling by jumpering R to G and R to Y/Y2 on furnace control
thermostat terminals. If outdoor temperature is below 70_F, turn off
circuit breaker to outdoor unit before running furnace in the cooling
cycle. Turn outdoor circuit breaker on after completing cooling
cycle. See Fig. 38.
NOTE: If R-W/W1 thermostat terminals are jumpered at the time
blower door switch is closed, blower will run for 90 sec before
beginning a heating cycle.
a. Perform component self-test as shown at the bottom of the
SERVICE label, located on the blower door.
b. Verify blower is rotating in the correct direction
18. If furnace is operating properly, RELEASE BLOWER DOOR
SWITCH. Remove any jumpers or reconnect any disconnected
thermostat leads. Replace blower door.
19. Turn on gas supply and cycle furnace through one complete heating
cycle. Verify the furnace temperature rise as shown in Adjustments
Section. Adjust temperature rise as shown in Adjustments Section.
Cleaning Burners and Flame Sensor
The following items must 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:
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 67)
!
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.
NOTE: Use a back-up wrench on the gas valve to prevent the valve
from rotating on the manifold or damaging the mounting to the burner
assembly.
Refer to Fig. 68.
BURNER SUPT. ASSY
BURNER ASSY
FLAME SENSOR
(BELOW BURNER)
Fig. 68 – Burner Assembly
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 the gas pipe from gas valve and remove pipe from the
furnace casing.
6. Remove individual wires from terminals on gas valve.
7. Disconnect Hot Surface Igniter (HSI) wires from HSI.
8. Disconnect Flame Sensor wire from Flame Sensor.
9. Support the manifold and remove the 4 screws that secure the
manifold assembly to the burner assembly and set aside. Note the
location of the green/yellow wire and ground terminal.
10. Inspect the orifices in the manifold assembly for blockages or
obstructions. Remove orifice and clean or replace orifice.
11. Remove the four screws that attach the top plate of the casing to the
furnace.
12. Raise top plate up slightly and prop it up with a small piece of wood
or folded cardboard.
13. Support the burner assembly and remove the screws that attach the
burner assembly to the heat exchanger cell panel.
14. Remove wires from both rollout switches.
15. Slide one-piece burner out of slots on sides of burner assembly.
16. Remove the flame sensor from the burner assembly.
17. (Optional) Remove the Hot Surface Igniter (HSI) and bracket from
the burner assembly.
18. Check igniter resistance. Nominal resistance is 40 to 70 ohms at
room temperature and is stable over the life of the igniter.
19. Clean burner with a brush and a vacuum.
20. Clean the flame sensor with fine steel wool (0000 grade). Do not
use sand paper or emery cloth.
67
WARNING
IGNITER
BRACKET, IGNITER
FLAME ROLLOUT
SWITCH
A11403