Freezer is cold but the refrigerator is only slightly cool; frost buildup on the back wall of the freezer.

Safety first: Unplug the appliance and protect the floor from melting ice.

Steps:

• 1. Manual defrost: Open the doors and allow all ice to melt completely. This may take several hours. Use towels to absorb the water.
• 2. Clear defrost drain: Locate the drain hole beneath the evaporator and ensure it is not blocked by ice or debris. Flush with warm water if necessary.
• 3. Inspect defrost components: After defrosting, access the evaporator area and check the defrost heater and thermostat as described in defrost-related error entries.
• 4. Replace faulty parts: Install a genuine V-ZUG defrost heater and/or thermostat if they fail continuity tests.
• 5. Monitor operation: After reassembly, monitor the appliance for several days. If frost rapidly returns, the main control board may not be controlling the defrost cycle correctly and may need replacement.

Warning: Do not use knives or screwdrivers to chip away ice; this can puncture refrigerant lines.