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Model MSCF Modular Small Cabinet Fan
®
Symptom Possible Cause Corrective Action
Blower fails to
operate
Blown fuse or open circuit breaker Replace fuse or reset circuit breaker and check amps
Broken fan belt Replace
Defective motor or capacitor Replace
Motor starter overloaded Reset starter and check amps
Motor overamps
Airflow too high Check airflow and adjust drives if needed
Static pressures are higher or lower
than design
If higher, ductwork should be improved
If lower, fan RPMs 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
Mixing box 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 RPMs with catalog data
Mixing box dampers closed Open and adjust
Dirty or clogged filters Clean or replace
Leaks in ductwork Repair
Elbows, or other obstructions may
restrict fan outlet
Correct or improve ductwork
Belt slippage Adjust belt tension
Unit running backwards
Correct as shown in System Start-Up section, Step #2,
page 10
Excessive dirt buildup on wheels Clean wheel
Too much airflow
Blower fan speed too high Check for correct fan RPM
Filter(s) not in place Install filters
Insufficient static pressure
(airflow resistance)
Induce static pressure into system ductwork
Excessive noise or
vibration
Wheel improperly aligned and rubbing on
housing
Center wheel
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 inch 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
Unbalanced wheel caused by excessive
dirt and grease buildup
Replace or rebalance
Sheaves eccentric or out-of-balance Replace or rebalance
Accumulation of material on wheel Clean wheel and housing
Foreign objects in wheel or housing Remove objects. Check for damage or unbalance.
Troubleshooting
NOTE
Before taking any corrective action, ensure unit is incapable of operation during repairs.