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8. Troubleshooting
Fault diagnosis
Symptom
Cause
Remedy
Pilot lamp does not turn
on, and the exhaust
blower does not run
Main power is not turned on
Turn on the main power
Defective exhaust blower key
switch
Replace the key and circuit board as an
assembly
Discontinued wire
Re-connect the discontinuity
Pilot lamp turns on, but
exhaust blower does not
run
The breaker does not turn on
Turn the breaker on
Defective magnetic contactor
Replace the magnetic contactor
Thermal relay tripped
Eliminate the cause of broken bearing,
or broken belt, and reset the thermal
relay
Defective thermal relay
Replace the thermal relay
Defective motor
Replace or repair the motor
Discontinued wire
Re-connect the discontinuity
Exhaust blower
develops the running
sound, but not
operating
Defective motor
Replace or repair the motor
Open-phase operation of motor
Check that the power supply
connection is single phase
Check there is a discontinuity in the
wiring
Large noise from exhaust
blower
Foreign object in exhaust blower Remove the foreign object
Runner contacts with casing
Repair the exhaust blower
Run-off of runner axis
Repair the exhaust blower
Loosened shaft stopper
Re-tighten
Defective motor
Replace or repair the motor
Reduced air flow
Low voltage
Check power supply. Check wiring
connections, and repair if a poor
contact exists.
Reversed rotating direction of
exhaust blower
Replace two of three wires of exhaust
blower each other
Unexpected resistance in the duct
system
Check the duct system, and remove the
cause of unexpected resistance
Defective motor
Replace or repair the motor
Large vibrations
Run-off of exhaust blower runner Repair the exhaust blower
Loosened
exhaust
blower
attaching screw
Re-tighten