L.B. White Guardian 2.0 Owner's Manual And Instructions page 17

NOTES:
a. Fan wheel to motor mount plate spacing must be ad-
justed to the clearance per Fig. 15 before tightening the
fan wheel to the motor shaft.
b. Make sure that set screw(s) of the fan are on the flats of
motor shaft when tightening.
FIG. 15
MOTOR MOUNT PLATE
MOTOR
3/8 in. AD/AW060
1/4 in. AD/AW100
Air Pressure Switch
The air pressure switch is located on the fan housing at
the motor end of the heater. It must work properly to allow
an ignition cycle. If the air pressure 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. 16 (AW250 shown)
1. Disconnect the clear tube from the air pressure switch.
2. Remove the two (2) sheet metal screws holding the
switch's bracket to the fan housing.
FIG. 16
AIR PRESSURE
SWITCH
Guardian 2.0 LP or Natural Gas Heater
FAN WHEEL
CLEARANCE
1/8 in. AD/AW250
3/16 in. AW325
Owner's Manual • Guardian 2.0
Igniter & Flame Sensor
(HSI - AW Models)
1. Generally, the igniter and flame sensor replacement
consists of cutting the shrink tubing to expose the con-
nector and removing its mounting screw.
2. Replacement of the heat shrink tubes (574311) after
service is necessary to ensure a corrosion free con-
nection.
3. See Fig. 17 for specific mounting screws to remove.
Hot Surface Igniter (HSI)
Testing
■ The igniter must be cold to perform the following test.
■ Remove the wires from the ignition control terminals
"HSI" and perform an ohm check across the wires.
■ This verifies circuit integrity of the igniter and its associ-
ated wiring and connections.
■ Ohm readings will vary somewhat, but generally will be
in the range of 50-55 ohms.
To replace the igniter:
■ Disconnect the male igniter connector from the female
wire harness connector.
■ Remove the igniter mounting screw (A).
Flame Sensor
1. Remove the sensor's screw (B) from its mounting
bracket. See Fig. 17. Clean the sensor rod with steel
wool or emery cloth. Rub briskly to remove build up of
dust, dirt and oxide.
2. Check the flame sensor's insulator base for cracks. If
cracks are found, replace the sensor.
FIG. 17
B
A
17