Troubleshooting
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Before taking any corrective action, ensure unit is incapable of operation during repairs. |
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Symptom | Possible Cause | Corrective Action |
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| Blown fuse or open circuit breaker | Replace fuse or reset circuit breaker and check amps |
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Blower fails to | Broken fan belt | Replace |
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operate | Defective motor or capacitor | Replace |
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| Motor starter overloaded | Reset starter and check amps |
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| Airflow too high | Check airflow and adjust drives if needed |
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| Static pressures are higher or lower | If higher, ductwork should be improved |
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| than design | If lower, fan RPMs should be lower |
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Motor overamps | Blower rotation is incorrect | Check rotation and correct |
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Motor voltage incorrect | Check motor nameplate and supplied voltage |
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| Motor horsepower too low | See specifications and catalog for fan curves to determine |
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| if horsepower is sufficient |
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| Shorted windings in motor | Replace motor |
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| Mixing box damper not fully open | Adjust damper linkage or replace damper motor |
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| System static pressure too high | Improve ductwork to eliminate losses using good duct |
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| Blower speed too low | Check for correct drives and RPMs with catalog data |
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| Mixing box dampers closed | Open and adjust |
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| Dirty or clogged filters | Clean or replace |
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Insufficient airflow | Leaks in ductwork | Repair |
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| Elbows, or other obstructions may | Correct or improve ductwork |
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| restrict fan outlet |
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| Belt slippage | Adjust belt tension |
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| Unit running backwards | Correct as shown in System |
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| page 10 |
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| Excessive dirt buildup on wheels | Clean wheel |
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| Blower fan speed too high | Check for correct fan RPM |
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Too much airflow | Filter(s) not in place | Install filters |
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Insufficient static pressure | Induce static pressure into system ductwork |
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| (airflow resistance) |
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| Wheel improperly aligned and rubbing on | Center wheel |
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| housing |
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| Loose wheel on shaft | Tighten wheel setscrew |
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| Loose motor or blower sheave | Tighten sheave setscrew |
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| Belts too loose | Adjust belt tension after 24 hours of operation |
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| Belts too tight | Loosen to maintain 3/8 inch deflection per ft. of span |
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| between sheaves |
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| Worn belt | Replace |
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Excessive noise or |
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Motor base or blower loose | Tighten mountings bolts |
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vibration |
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Worn bearings | Replace |
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| Bearing and drive alignment | Realign |
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| Motor out of balance | Replace |
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| Unbalanced wheel caused by excessive | Replace or rebalance |
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| dirt and grease buildup |
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| Sheaves eccentric or | Replace or rebalance |
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| Accumulation of material on wheel | Clean wheel and housing |
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| Foreign objects in wheel or housing | Remove objects. Check for damage or unbalance. |
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®
Model MSCF Modular Small Cabinet Fan 11
