Condenser Fan Motor Failure RTAE/ACR

Issue: 

Condenser Fan Motor Failure / Bearing Wear

Discussion / Resolution:

• Pueblo Technical Support has identified a potential issue in the field with RTAE condenser fan motor (and fan blade) failure.
• Early warning and quality containment has not shown a reliability issue; however, there have been customer chillers where we have seen early or premature failure of condenser fan motors.
• During field investigation we have witnessed condenser fan blades wobbling, indicating a balance issue.
  • Field balancing of fans was attempted initially.
  • Some fans were able to be balanced.
  • Fans that could not be balanced were replaced.
  • Until 4-20-2017 fans manufactured could still have an issue with shaft perpendicularity as well as run out. So fans were replaced and had to be balanced
• Further investigation of the motors has shown two other issues:
  • Snap Ring is not present in the groove on the motor shaft to hold the fan blade in proper position
  • Snap Ring deformation due to improper installation on fan motor shaft
• Bearing/Housing failure can be observed by attempting to move the blade up and down in a vertical motion.  If there is movement or a wobble, one or more of the bearings or housing has failed in the motor.
• Investigation of the Fan blade yielded interesting results; where we found the sleeve ( fan blade hub ) not perpendicular to the fan motor shaft, resulting in excessive run-out and no possibility to properly balance the fan-blade, stressing the motor.
• See drawings below for reference  (notice failure during manufacturing of sleeve/hub installation):

                             FAN BLADE:                                                 

HUB/SLEEVE:  PASS

HUB/SLEEVE:  FAIL

Fans with manufacturing date code 4-20-2017 and newer have improved tooling and quality control processes that corrected the shaft alignment, run out and unbalance issues.

Recommended action in the field if fan motor failure occurs:

• Currently if a fan motor failure occurs due to a balance issue with the fan blade, follow the procedure below:
  • If the existing fan blade was manufactured after 4-20-2017 contact Pueblo Technical Support. Example of date stamp below
    
  • If blade was manufactured prior to this date then replace motor and fan blade.
  • Validate new fan blade date code is post 4-20-2017
  • Validate Snap Ring is installed properly. The opening in the snap should be 180 degree's away from the keyway groove on the motor shaft.
  • Properly torque fan blade bolt. 16 ft-lbs.

EXAMPLE DATE IN PHOTO SHOWS: 11-03-2014

  Notes:

• Fan Motor BLADE Snap Ring (used to support the fan blade and spacing on the motor shaft):
  • Missing or improperly placed snap ring results in FAN BLADE rubbing on the orifice.
  • Fan bolt torque 15 ft.-lbs.

  Fan Blade Manufacturer History:

• Kenco   - Nov 2013 - May 2016
• Kings    - May 2016 - Sep 2018
• Lomont - Dec 2018 - Present

  Other Question/Problem/Cause Statements:

• Fan motor failure
• Fan failure
• Condenser Fan Failure
• Motor Failure
• Condenser Motor Failure

  Facts:

• RTAE (Air Cooled Chiller) -  Pueblo
• ACR (Air Cooled Chiller) - Pueblo

Original HUB Document : DOC-137167