L.B. White Guardian Series, Owner'S Manual And Instructions, Page: 20 / 144

Guardian with Smart Sense™
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Owner’s Manual • Guardian
20
BURNER
FLAME
BURNER
CASTING
FLAME SENSOR
3/8 TO 1/2 IN.
FIG. 11
MOTOR MOUNT PLATE
FAN WHEEL
MOTOR
CLEARANCE
Air Proving Switch
The air proving switch is located on the fan housing
at Fig. 12 the motor end of the heater. It must work
properly to allow an ignition cycle. If the air proving
switch contacts are closed before the ignition control
starts the fan motor, or do not close on a call for
heat after the fan motor starts, ignition will not occur.
See Fig. 12.
To service:
-- Remove the two (2) sheet metal screws holding
the switch with bracket to blower housing.
-- Remove the assembly by turning the switch
so the paddle on the switch arm can be pulled
through the oblong hole on side of fan housing.
FIG. 12
Igniter (HSI)
1. See Fig. 13 for location.
2. Generally, igniter replacement consists of removing
its mounting screw and cutting the shrink tubing to
expose the male igniter connector and female wire
harness connector. (Speci
fi c change-out instructions
accompany the replacement igniter).
Testing
■ Perform an ohm check at the ignition control terminals
HSI and HSIG when the igniter is cold.
■ This veri fi es circuit integrity of the igniter and its as-
sociated wiring and connections.
■ Ohm readings will vary somewhat, but generally will be
in the range of 50-55 ohms.
Flame Sensor (HSI)
1. Remove the sensor from its mounting bracket. See
Figs. 13 and 14. Clean the sensor rod with steel wool
or emery cloth. Rub briskly to remove build up of dust,
dirt and oxide.
FIG. 13
2. Check the fl ame sensor’s insulator base for cracks. If
cracks are found, replace the sensor.
3. Position the fl ame sensor as shown in Fig. 14.
FIG. 14
AD060/100 - 3/16 IN.
AW060/100 - 3/16 IN.
AD/AW250 - 1/8 IN.
SENSOR
SCREW
FEMALE
CONNECTOR MALE
CONNECTOR
BURNER
BRACKET
IGNITER