Viessmann Outdoor Fan or Compressor Mechanical Noise

Outdoor unit very noisy (grinding or scraping) when running

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Worn outdoor fan motor bearings, Fan blade hitting shroud or grille, Loose compressor mounting bolts, Failing compressor

How to Fix / Troubleshooting

Safety: Isolate power at the outdoor disconnect before inspection.

  • Inspect fan blade: Check for bent blades or objects stuck in the fan. Straighten minor bends carefully or replace the blade.
  • Check fan motor play: Wiggle the fan hub; excessive play indicates worn bearings and the motor should be replaced.
  • Compressor mounts: Tighten compressor mounting bolts and ensure rubber isolators are intact.
  • Compressor noise: If the compressor itself is extremely loud (knocking or metallic sounds), consult a technician; compressor replacement may be required.
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Repair Difficulty

Hard 4/5

Required Part

Outdoor Fan Motor
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