Page 71 of 84
Problem
Probable Cause
Solution
Blower Motor Does
Not Run
Damper limit switch not closed
or inoperative
Repair or replace switch
Motor thermal overloads tripped
For tripped condition-reset
Fuses blown or missing
Replace
External power source lacking
Have incoming power lines checked
Motor inoperative
Repair or replace
Blower Motor Runs,
But Fans Do Not
Supply Enough
Make-Up Air
Intake filters dirty
Replace or clean
Obstruction in intake
Check dampers for proper operation
Clear all intake passages of obstructions
Fan wheel loose on shaft
Reposition and tighten
Access doors and panels not closed
Close
Excessive discharge resistance from:
Dirty filters in discharge
External dampers
Clean filters and/or readjust dampers
Excessive Fan Noise
Fan bearing
Replace
Fan wheel loose on shaft
Reposition and re-tighten
Fan wheel rubbing
Loosen setscrews Reposition cone
and tighten
Fan wheel dirty
Clean
Loose duct
Tighten or reinforce
Foreign article in fan or duct
Remove
Table 13.1: Supply Fan
PR Series Installation, Operation, and Maintenance Manual
