Troubleshooting - Unit
Symptom Possible Cause
Corrective Action
Excessive
noise or
vibration
Fan wheel rubbing on inlet.
Adjust wheel and/or inlet cone. Tighten wheel hub or
bearing collars on shaft.
Bearings.
Replace defective bearing(s). Lubricate bearings.
Tighten collars and fasteners.
Wheel out of balance.
Replace or rebalance.
Loose wheel on shaft.
Tighten wheel hub.
Loose blower or motor sheave.
Tighten sheave setscrew.
Belts too loose.
Adjust belt tension after 24 hours of operation.
Belts too tight.
Loosen to maintain a 1/64-inch deflection per foot of
span between sheaves.
Worn belt.
Replace.
Motor base or blower loose.
Tighten mounting bolts.
Bearing and drive misaligned.
Realign.
Noise being transmitted by duct.
Make sure ductwork is supported properly. Make sure
ductwork metal thickness is sized for proper stiffness.
Check duct size at discharge to ensure that air
velocities are not too high.
Intermediate shipping rails attached to
blower assembly.
Remove intermediate shipping rails. See assembly
page 8 of this document.
Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist prior to
requesting parts or service information.
30
Model MPX Make-Up Air Unit
Model XMPX Make-Up Air Unit