Freezer display shows dF and unit may not defrost properly, leading to frost buildup

Safety first: Unplug the freezer before accessing internal components or removing panels. Use caution around sharp evaporator fins.

• Check for heavy frost: Remove freezer drawers and the rear interior panel to inspect the evaporator coil. A solid block of ice indicates a defrost failure.
• Manual defrost: To restore temporary cooling, allow the unit to defrost fully by unplugging it and leaving doors open for 24–48 hours. Place towels to catch water. Do not use sharp tools to chip ice.
• Test defrost heater: With the evaporator exposed and power disconnected, locate the defrost heater at the base or around the evaporator. Disconnect its wiring and test for continuity with a multimeter. Replace the heater if open.
• Check defrost thermostat/bi-metal: The thermostat is clipped to the evaporator tubing. When the coil is cold (below freezing), it should show continuity. If it remains open when cold, replace it.
• Inspect evaporator thermistor: Café freezers use thermistors for temperature feedback. Measure its resistance at a known temperature and compare to service specs (typically ~16–20 kΩ at 32°F/0°C). Replace if readings are far out of range.
• Control board evaluation: If heater and sensors test good, the main control board may not be initiating defrost. Board replacement is usually required and may need a technician.