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Sub-Zero Automatic Defrost Operation


  • Does a Sub-Zero unit have to be manually defrosted?
  • When does a Sub-Zero unit defrost?
  • Is there an automatic defrost feature on a Sub-Zero?


Sub-Zero refrigerator and freezer sections have an automatic defrost feature and should not require manual defrosting under normal operating conditions.

Defrost duration varies by product. Older products have a set defrost duration, and units with electronic controls have an adaptable defrost. See below for more information:

  • 600, 700, Classic Series (BI), Designer Series (IT, IC, ID), UC Undercounter, and 648PRO units:
    • Freezer section is controlled by an energy-saving adaptive defrost system and defrosts as needed.
    • Refrigerator section will defrost during each off cycle of the refrigerator compressor.
  • 200/300 and 500 Series units:
    • Freezer section automatically defrosted based off compressor runtime.
    • Depending upon model, compressor runtime ranged from 6 hours 21 minutes, 12 hours, or 24 hours.
    • Refrigerator section did not have an automatic defrost feature. Defrosting should not be required under normal operation.
  • For units with electronic controls, the temperature change during defrost will not show as a rise in temperature on the display since it only provides an average temperature over time.

Refer to the product Use and Care Guide for further information.

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