Wine cooler shows E4 and the compressor and fan may stop; unit may not restart until power is cycled.

Warning: Always disconnect power before working on the defrost system. Components can be hot and electrically live.

• Access evaporator and defrost components: Remove interior shelves and the rear inner panel to expose the evaporator coil, defrost heater, and defrost sensor.
• Inspect for heavy ice buildup: If the evaporator is encased in ice, allow it to fully defrost by unplugging the unit and leaving the door open for several hours. Place towels to catch melt water.
• Check defrost sensor: Locate the defrost NTC sensor attached to the evaporator. Test its resistance at room temperature and in ice water. Replace if readings are open, shorted, or inconsistent.
• Test defrost heater: With the unit unplugged, disconnect the heater leads and measure resistance. A typical heater will show a finite resistance (e.g., 50–300 Ω). An open circuit indicates a failed heater that must be replaced.
• Inspect thermal fuse/thermostat: Some Teka models include a thermal fuse or bimetal thermostat in series with the heater. Test for continuity; replace if open.
• Reassemble and test: After replacing any faulty parts, reassemble the interior panel, restore power, and monitor for recurrence of E4.
• PCB diagnosis: If all defrost components test good, the main control PCB may not be initiating or terminating defrost correctly and should be replaced by a qualified technician.