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Symptom
Blower fails
Blown fuse or open circuit breaker
to operate
Broken fan belt
Defective motor or capacitor
Motor starter overloaded
Motor overamps
CFMs too high
Static pressures are higher or lower
than design
Blower rotation is incorrect
Motor voltage incorrect
Motor horsepower too low
Shorted windings in motor
Insufficient airflow
Unit damper not fully open
System static pressure too high
Blower speed too low
Dampers or registers closed.
Dirty or clogged filters
Leaks in ductwork.
Elbows, or other obstructions
may restrict fan outlet.
Belt slippage
Too much airflow
Blower fan speed too high
Filter(s) not in place.
Insufficient static pressure (SP)
(airflow resistance)
Excessive noise
Wheel rubbing on housing
or vibration
Loose wheel on shaft
Loose motor or blower sheave
Belts too loose
Belts too tight
Worn belt
Motor base or blower loose
Worn bearings
Bearing and drive alignment
Motor out of balance
Wheel out of balance
Sheaves eccentric or out of balance
Accumulation of material on wheel
TROUBLE SHOOTING
Blower Unit
Possible Cause
Corrective Action
Replace fuse or reset circuit breaker and
check amps
Replace
Replace
Reset starter and check amps
Check CFMs and adjust drives if needed
If higher, ductwork should be improved
If lower, fan RPMs should be lower
Check rotation and correct
Check motor nameplate and supplied voltage
See specifications and catalog for fan
curves to determine if horsepower is sufficient.
Replace motor.
Adjust damper linkage or replace
damper motor
Improve ductwork to eliminate losses
using good duct practices
Check for correct drives and RPMs
with catalog data
Open and adjust
Clean or replace
Repair
Correct or improve ductwork
Adjust belt tension
Check for correct fan RPM
Install filters
Induce SP into system ductwork.
Center wheel
Tighten wheel setscrew
Tighten sheave setscrew
Adjust belt tension after 24 hours
of operation
Loosen to maintain 3/8" deflection
per ft. of span between sheaves
Replace
Tighten mountings bolts
Replace
Realign
Replace
Replace or rebalance
Replace or rebalance
Clean wheel and housing
17
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