Ice or Frost Build-Up in Freezer


  • Freezer door left ajar 
  • Freezer drain tube frozen
  • Torn gasket
  • Ice maker not filling properly

Core Issue:

  • How to manually defrost the freezer section?
  • Ice or frost building up inside top area of freezer section
  • Ice on the back wall of the freezer
  • What can cause frost in the freezer of a Sub-Zero unit?
  • Freezer shelves, drawers or bins have condensation or fog or freezing over
  • Moisture in freezer
  • Freezer basket or drawer rails frozen over

Steps to Verify Issue:

For any frost or ice build-up in a Sub-Zero freezer, follow these steps:

  1. Verify the door was not left ajar for a period of time.
  2. Remove anything obstructing the door from closing.
  3. Some condensation inside a unit or on the shelving or drawers is normal if the door is opened or left open for a period of time.
    • In warm climates, this will be noticeable more quickly.
    • Keep the door closed and fogging will resolve on its own.
  4. Inspect door gaskets for tears, rips or dry rot; replace if cracked, torn, etc.
  5. Clean the condenser if not done in the last 3 months.
  6. Check set point temperatures for the compartment, see Measuring Temperatures in a Refrigerator or Freezer.
    • On an electronic control panel, recommended freezer temperature is 00° F.
    • For a dial control, set the dial between 4 – 6, 1 is warmest, 10 is coldest, 0° F is suggested.
  7. If the drain tube is frozen, see:
  8. Defrost the freezer, see Manually Defrost a Sub-Zero for instructions.
  9. See also, Freezer Burn on Food and Door Difficult to Close.
  10. Wait 24 hours for the unit to return to normal temperatures and frost to clear after correcting any of the above.


If these steps do not resolve the issue, no further troubleshooting advice is available. Contact Factory Certified Service to schedule an appointment for repair.

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