Bosch Compressor Not Starting

Freezer not cooling at all; interior is warm, compressor not running, display may be on.

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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

Failed compressor start relay or PTC, Defective compressor motor, Faulty main control board not sending start signal, Open thermal overload on compressor

How to Fix / Troubleshooting

Safety: Unplug the freezer before accessing the compressor area. High voltage and hot surfaces are present when running.

Steps:

  • Listen for activity: After plugging in, listen for a humming or clicking from the compressor. Repeated clicking without running suggests start device issues.
  • Access compressor: Remove the rear lower cover to expose the compressor and start device.
  • Inspect start relay/PTC: Remove the plastic start device from the compressor terminals. Shake it gently; if it rattles or shows burn marks, it is likely faulty.
  • Test compressor windings: With power disconnected, measure resistance between compressor terminals. All readings should be finite and not shorted to ground. If windings are open or shorted, the compressor is defective.
  • Replace start device: If the compressor tests good, install a Bosch-compatible start relay/PTC and overload protector.
  • Control board check: If the compressor and start device are good but never receive power, the main control module may be faulty and require replacement.

Warning: Compressor replacement and refrigerant handling must be done by a certified refrigeration technician.

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Repair Difficulty

Professional Required 5/5

Required Part

Compressor Start Relay / PTC
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