- Faulty door gasket
- Air leaking into the unit
- Air circulation issue
- Sealed system issue
- Clogged drain tube
- Ice forms on back wall or floor of refrigerator
- Ice forms at the back of the crisper shelf assembly
- Ice behind the refrigerator drawers
Steps to Verify Issue:
For all Sub-Zero models except 648PRO, follow the instructions below. For model 648PRO, see 648PRO Refrigerator Evaporator Icing Up.
- Remove any obstructions preventing a proper door seal and verify the door closes all the way.
- Check the set temperatures are at or near 38°F in the refrigerator and 0°F in the freezer, or set between 4 and 6 if the unit has a dial control.
- Clean the Condenser if it has not been done in the last 6 months. It could take up to 24 hours for the unit to respond once the condenser is clean.
- Open the refrigerator door and inspect the unit door gasket. If it is ripped, torn, or damaged, replace it. See Sub-Zero Door Gasket Replacement.
- Remove the crisper drawer and crisper shelf assembly. If equipped, remove all lower storage drawers. If there is ice buildup, food debris, or standing water in the drain tube or trough along the back wall, clean the drain tube.
- The drain trough and drain tube are visible on a 200, 300, 500, or 600 Series. See 200, 300, 500, 600 Series Refrigerator Drain Tube Cleaning.
- For 400 Wine Storage, 700 Series, 648PRO, and Classic (formerly Built-In) Series, refer to Classic, 700, 400, 648PRO Series Drain Tube Cleaning.
- For heavy ice buildup, defrost the unit. Refer to Manually Defrost a Sub-Zero for instructions.
- If ice or frost returns after following the above steps, service is necessary to expertly diagnose and repair the product. Contact Factory Certified Service to schedule an appointment for repair.
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