Siemens Compressor Start Failure

Freezer makes a loud buzzing or clicking noise and then stops; compressor does not stay 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

Defective PTC start relay, Weak or failed run capacitor, Overload protector tripping due to high start current, Seized compressor

How to Fix / Troubleshooting

Safety: Unplug the freezer before accessing the compressor electrical box. Mains voltage is present.

  • 1. Access compressor components: Remove the rear lower panel and the plastic cover on the compressor terminals.
  • 2. Inspect start relay and overload: Look for burn marks, cracks, or melted plastic. A rattling sound when shaking the PTC relay (disconnected) can indicate failure.
  • 3. Replace start components: Install a new Siemens-compatible start relay and overload protector, and run capacitor if fitted.
  • 4. Test operation: Refit covers, restore power, and listen for the compressor starting and continuing to run.
  • 5. If still failing: If the compressor still hums briefly and trips, the compressor itself may be mechanically seized and will require replacement by a refrigeration technician.

Note: Repeated start attempts can overheat and damage the compressor; limit testing until proper components are installed.

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Repair Difficulty

Hard 4/5

Required Part

Compressor Start Relay and Overload Protector
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