Thick frost buildup on the evaporator coil behind the rear interior panel; airflow is weak and cooling is poor.

Safety first: Unplug the freezer before removing panels or testing electrical components. Coils and fins are sharp.

Steps to restore defrost:

• 1. Defrost manually: Remove food and shelves, then the rear panel. Use towels and a hair dryer on low to melt all ice from the evaporator and drain area.
• 2. Locate defrost components: Identify the defrost heater (at the bottom or woven through the coil) and the defrost thermostat clipped to the tubing.
• 3. Test heater: Disconnect heater leads and measure resistance. An open circuit indicates a failed heater that must be replaced.
• 4. Test thermostat: While still cold, check continuity across the thermostat. It should be closed when cold. Replace if open.
• 5. Check timer/control: On mechanical-timer RCA models, locate the defrost timer (often near the compressor or control housing) and try advancing it with a screwdriver to see if it switches between cooling and defrost. If it does not advance or switch, replace it. On electronic models, a faulty main control board may be responsible.
• 6. Repair wiring: Inspect harnesses for breaks or burned connectors and repair as needed.
• 7. Reassemble and monitor: After replacing failed parts, reassemble and monitor for several days to ensure frost does not return.

Warning: Do not chip ice off the evaporator with sharp tools; you can puncture the refrigerant lines and ruin the freezer.