How to Fix PowerFlex 753/755 Fault 32 Fan Feedback Lost?

PowerFlex 753/755 Fault 32 – Fan Feedback Lost indicates that the drive is not receiving the expected feedback signal from one or more cooling fans. The PowerFlex 753/755 continuously monitors its cooling fans to ensure adequate airflow for the power module. If the fan stops, becomes disconnected, or its feedback signal is lost, the drive generates Fault 32 to protect the inverter from overheating.

How to Fix PowerFlex 753/755 Fault 32 Fan Feedback Lost?


This fault generally indicates a problem with the cooling fan, fan feedback circuit, or fan wiring, rather than the motor or application.

Possible Causes

  • Cooling fan failure.
  • Fan feedback signal lost.
  • Fan connector is loose or disconnected.
  • Damaged fan wiring.
  • Fan blocked by dust or debris.
  • Worn or seized fan bearings.
  • Defective fan feedback circuit.
  • Internal control board fault (less common).
  • Fan power supply problem.
  • Excessive dust causing restricted airflow.

Solutions

  1. Inspect the cooling fan and verify that it rotates freely.
  2. Check the fan connector and wiring for loose or damaged connections.
  3. Remove dust or debris from the fan and heatsink.
  4. Verify that the fan is receiving the correct supply voltage.
  5. Replace the cooling fan if it is defective or not operating.
  6. If the fan operates correctly but the fault remains, inspect the fan feedback circuit or control board.
  7. Reset the fault and verify normal drive operation.

Additional Information

The PowerFlex 753/755 uses internal cooling fans to maintain safe operating temperatures for the power electronics.

Fault 32 – Fan Feedback Lost is generated when the drive no longer detects the expected fan feedback signal. Even if the fan appears to rotate, a failed feedback sensor or wiring problem can still trigger this fault.

If the cooling fan is not repaired promptly, the drive may eventually experience overtemperature faults due to insufficient airflow.

Common Symptoms

  • Drive displays Fault 32 – Fan Feedback Lost.
  • Cooling fan does not rotate or rotates intermittently.
  • Reduced airflow through the heatsink.
  • Drive may shut down to prevent overheating.
  • Abnormal fan noise.
  • Fault occurs during startup or while running.
  • Repeated fan-related faults after reset.
  • Drive temperature gradually increases.
  • Reduced drive reliability if left uncorrected.
  • Motor operation stops until the fault is cleared.

Recommended Troubleshooting Sequence

  1. Verify that the fault is 32 – Fan Feedback Lost.
  2. Disconnect power and follow lockout/tagout procedures.
  3. Inspect the cooling fan for free rotation.
  4. Check the fan connector and wiring.
  5. Clean the fan and heatsink of dust and debris.
  6. Measure the fan supply voltage.
  7. Replace the cooling fan if it is faulty.
  8. Inspect the fan feedback circuit if the fault persists.
  9. Restore power and reset the fault.
  10. Verify proper fan operation and monitor the drive temperature.

Fault 32 Fan Feedback Lost Check Table

Check PointAction
Cooling fanVerify proper operation
Fan bladesCheck for obstruction or damage
Fan connectorEnsure secure connection
Fan wiringInspect for damage
Fan power supplyVerify correct voltage
Fan feedback circuitInspect if fault persists
HeatsinkClean accumulated dust
Drive operationConfirm normal cooling after repair

Preventive Maintenance Tips

  • Clean cooling fans and heatsinks regularly.
  • Inspect fan wiring and connectors during preventive maintenance.
  • Replace cooling fans at the manufacturer's recommended service interval.
  • Maintain adequate ventilation around the drive.
  • Keep electrical enclosures free of dust and contaminants.
  • Monitor drive temperature during normal operation.
  • Replace noisy or slow-running fans before failure.
  • Record recurring Fault 32 events to identify deteriorating cooling components.
  • Ensure enclosure filters are clean to maintain proper airflow.
  • Follow Rockwell Automation preventive maintenance recommendations for PowerFlex 753/755 drives.

Proper inspection of the cooling fan, fan feedback circuit, fan wiring, fan power supply, and heatsink airflow will help prevent recurring PowerFlex 753/755 Fault 32 – Fan Feedback Lost, ensuring reliable cooling, protecting the drive from overheating, and extending the service life of the inverter.

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