Service Instructions; General; Motor & Fan Assembly - L.B. White GUARDIAN Smart Sense AD250 Owner's Manual And Instructions

WARNING
Burn Hazard
■
Heater surfaces are hot for a period of time after the
heater has been shut down.
■
Allow the heater to cool before performing service,
maintenance, or cleaning.
■
Failure to follow this warning will result in burns
causing injury.
WARNING
Fire and Explosion Hazard
■
Do not disassemble or attempt to repair any heater
components or gas train components.
■
All component parts must be replaced if defects are
found.
■
Failure to follow this warning will result in fire or
explosions, causing property damage, injury, or death.
1. Close the fuel supply valve to the heater and
disconnect the electrical supply before servicing
unless necessary for your service procedure.
2. Open appropriate case panel for access to heater
components.
3 Disconnect the appropriate electrical leads for the
component being replaced.
1. Remove the screws securing the motor mounting
plate to the fan housing.
2. Pull the fan and motor assembly from the housing.
3. Loosen the square head set screw(s) on the fan
wheel with a wrench.
4. Pull the fan wheel from the motor shaft. Use a wheel
puller if necessary.
5. Remove the four (4) nuts securing the motor to the
mounting plate.
a. Fan wheel to motor mount plate spacing must
be adjusted to proper clearance before
tightening the fan wheel to the motor shaft.
b. Ensure set screw(s) of the fan are on the flats
of motor shaft when tightening.

Service Instructions

4. The high limit heat switch will open if it overheats. It
must be manually reset. If the high limit switch does
not reset, it can be tested by jumpering the switch out
of the electrical circuit.:
-- Reconnect the electrical supply and open fuel
supply valves.
-- If the heater lights, the component is defective and
must be replaced.
-- Do not operate the heater with the switch jumpered.
Replace the part immediately.
-- An alternate method for checking the components
is to perform a continuity check.
5. Do not jumper the air proving switch before the fan
motor is started by the ignition control. If jumpered,
the ignition control will not allow heater operation.
Test the air proving switch for continuity. If defective,
replace the switch
6. For reassembly, reverse the respective ser vice
procedure. Ensure gas connections are tightened
securely.
7. After servicing, start the heater to ensure proper
operation. Check for gas leaks with approved leak
detectors.
8. Clean the heater's orifice with compressed air or a
soft, dry rag. Do not use files, drills, broaches, etc. to
clean the orifice. Doing so may enlarge the hole,
causing combustion or ignition problems. Replace the
orifice if it cannot be cleaned properly.
MOTOR AND FAN WHEEL ASSEMBLY
FIG. 11
MOTOR MOUNT PLATE
MOTOR

GENERAL

FAN WHEEL
CLEARANCE
1/8 - 3/16 In.
15