- 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:
- Remove door obstructions that may prevent a proper seal and verify the door closes all the way.
- Check the set temperatures are at or near 38°F in the refrigerator, 0°F in the freezer, or 4-6 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.
- For heavy icing, turn off the unit and use a hair dryer on low to remove the ice.
- 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.
- Address error codes if any are present on the display. Search for error code information separately.
- For model 648PRO or PRO48, see 648PRO Refrigerator Evaporator Icing Up.
- Remove the crisper drawer and crisper shelf assembly; if equipped, remove all lower storage drawers. If ice is in the crisper area, a drain issue is more likely than if the frost is in the shelf area.
- Food debris, standing water, or ice built up in the drain trough or drain tube located along the back wall may cause frost if the drain tube is clogged.
- 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 Built-In (BI) Series, refer to Drain Tube Cleaning (BI, 700, 400, 648PRO Series).
If ice or frost returns after following the above steps, no further troubleshooting advice is available. Contact Factory Certified Service to schedule an appointment for repair.
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