30
Troubleshooting
SYMPTOM SOURCE PROBABLE CAUSE
1. Impeller hitting inlet ring
• Impeller not centered (check shaft clamp).
• Inlet ring damaged or not adjusted.
• Shaft loose in bearing (check locking Collar).
• Impeller loose on shaft (check shaft clamp).
• Bearing loose in bearing support (check mounting bolts).
2. Drive
• Sheave not tight on shaft (motor or fan).
• Belts loose. Adjust after 48 hours operation.
• Belt too tight.
• Belt wrong cross section.
• Belt not matched in length on multi-belt drive.
• Variable pitch sheaves not adjusted so each groove
has the same pitch diameter (multi-belt drives).
• Sheaves misalign.
• Belt worn.
• Motor, motor base or fan not securely anchored.
• Belt oily or dirty.
3. Bearing
• Defective bearing.
• Needs lubrication.
• Loose on bearing support.
• Loose on shaft (check locking collar).
• Misalign (check alignment binding).
• Foreign material inside bearing.
• Worn bearing.
• Fretting corrosion between inner race and shaft.
4. Impeller
• Loose on shaft (check shaft clamp).
• Defective impeller. Do not run fan. Contact manufacturer.
• Unbalance.
• Foreign material on fan blades.
5. Housing
• Foreign material in housing.
• Inlet cones loose or not fan blades.
6. Electrical
• Lead-in cable is not secure or is too rigid.
• AC hum in motor or relay.
• Starting relay chatter.
• Motor bearings.
• Single phasing a 3-phase motor.
7. Shaft
• Bent or undersized. May cause noise at impeller,
bearings or sheave.
• Loose internal balance weights.
• Bearing alignment.
Noise
8. High air velocity
• Ductwork too small.
• Fan running too small.
• Fan selection too small.
• Static pressure lower than expected.
• Registers and grilles too small.
• Insufficient face area of heating or cooling coil.
To Next Page
Loading...
Need help?
General
