31
Symptom
Possible Cause
Solution
Blower fails
Blown fuse or open circuit breaker
Replace fuse or reset circuit breaker and
to operate
check amps
Broken fan belt
Replace
Defective motor or capacitor
Replace
Motor starter overloaded
Reset starter and check amps
Motor overamps
cfm too high
Check cfm and adjust drives if needed
Static pressures are higher or lower
If higher, ductwork should be improved
than design
If lower, fan rpm should be lower
Blower rotation is incorrect
Check rotation and correct
Motor voltage incorrect
Check motor nameplate and supplied voltage
Motor horsepower too low
See specifications and catalog for fan
curves to determine if horsepower is sufficient.
Shorted windings in motor
Replace motor.
Insufficient airflow
Unit damper not fully open
Adjust damper linkage or replace
damper motor
System static pressure too high
Improve ductwork to eliminate losses
using good duct practices
Blower speed too low
Check for correct drives and rpm
with catalog data
Dampers or registers closed.
Open and adjust
Dirty or clogged filters
Clean or replace
Leaks in ductwork.
Repair
Elbows, or other obstructions
Correct or improve ductwork
may restrict fan outlet.
Belt slippage
Adjust belt tension
Too much airflow
Blower fan speed too high
Check for correct fan rpm
Filter(s) not in place.
Install filters
Insufficient static pressure (Ps)
Induce Ps into system ductwork.
(airflow resistance)
Excessive noise
Wheel rubbing on housing
Center wheel
or vibration
Loose wheel on shaft
Tighten wheel setscrew
Loose motor or blower sheave
Tighten sheave setscrew
Belts too loose
Adjust belt tension after 24 hours
of operation
Belts too tight
Loosen to maintain
3
⁄
8
in. deflection
per ft. of span between sheaves
Worn belt
Replace
Motor base or blower loose
Tighten mountings bolts
Worn bearings
Replace
Bearing and drive alignment
Realign
Motor out of balance
Replace
Wheel out of balance
Replace or rebalance
Sheaves eccentric or out of balance
Replace or rebalance
Accumulation of material on wheel
Clean wheel and housing
31
Trouble Shooting Instructions:
Blower System
