Display shows dF or DEF; freezer may pause cooling briefly while code is shown.

Safety: No immediate hazard. Do not unplug during a normal defrost unless troubleshooting.

Steps:

• Determine if normal: Many Vissani freezers briefly display dF during scheduled defrost. This should last 15–30 minutes and then return to normal display.
• Monitor duration: If dF remains for more than 1 hour and the compressor does not restart, suspect a stuck defrost condition.
• Power reset: Unplug the freezer for 5–10 minutes, then plug back in. If dF immediately returns and cooling does not resume, further diagnosis is needed.
• Check defrost thermostat: Access the evaporator and test the defrost thermostat. If it remains closed when warm, it may be causing extended defrost.
• Control board: If the thermostat is good, the main control board defrost logic may be faulty and require replacement.

Note: If temperatures remain safe and dF appears only occasionally, it is likely normal operation.