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935SB: Installation, Start-up, Operating and Service Maintenance Instructions
Fig. 67 – Blower Assembly on
66100M21
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.
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:
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.
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
When servicing the flame sensor, only use the factory-provided 1/4-in.
length screws. Use of alternate screws will damage unit components.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 68 – Igniter Position - Back View
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 burner assembly.
a. Using a 1/4-in. driver, remove the screw securing the flame
sensor to the burner assembly (see
factory-provided 1/4-in. screws.
b. Carefully withdraw the flame sensor from the burner assembly
without striking the sensor on surrounding parts.
c. Inspect flame sensor for signs of damage or failure.
d. Clean the flame sensor with fine steel wool (0000 grade). Do not
use sand paper or emery cloth.
e. If replacement is required, remove the screw that secures the
A190407
flame sensor on the bracket and remove the flame sensor.
7. To replace flame sensor and bracket assembly, reverse items 6a
through 6d.
8. Reconnect flame sensor wire to the wire harness, dressing the
sensor wires to ensure there is no tension on the flame sensor itself
(see
Fig.
68).
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Never purge a gas line into a combustion chamber. Never test for gas
leaks with an open flame. Use a commercially available soap solution
made specifically for the detection of leaks to check all connections. A
fire or explosion may result causing property damage, personal injury
or loss of life.
9. Turn gas on at electric switch on gas valve and at external shut-off
or meter
10. Turn power on at external disconnect, fuse or circuit breaker.
11. Run the furnace through two complete heating cycles to check for
proper operation
12. Install control door when complete.
Servicing Hot Surface Igniter
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
When servicing the flame sensor, only use the factory-provided 1/4-in.
length screws. Use of alternate screws will damage unit components.
The igniter does NOT require annual inspection. Check igniter
resistance before removal (see
58
Fig.
68). Retain
WARNING
!
WARNING
!
Fig.
68).
A190266
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