Unit shows E4 and may stop cooling; sometimes accompanied by ice buildup on the evaporator or frequent defrost cycles.

Safety: Disconnect power before removing covers. Avoid using sharp tools to remove ice.

Steps to address E4:

• Check filter and airflow: Remove and clean the air filter with warm soapy water. Ensure front grille, intake, and discharge vents are not blocked by curtains, furniture, or dust.
• Inspect evaporator for ice: Remove the front grille and look at the evaporator coil. If heavily iced, leave the unit unplugged with the front cover open until all ice melts (place towels to catch water).
• Verify fan operation: With the unit reassembled, briefly power on and confirm the indoor fan runs at all speeds. A non-spinning or weak fan can cause icing and E4.
• Check evaporator sensor: Follow the same procedure as for E2 to ensure the sensor is properly attached and reading correctly. Replace the evaporator thermistor if faulty.
• Reset and test: After clearing ice and ensuring good airflow, reset power and run the unit. If E4 returns quickly, the control PCB may be misreading sensor data.

Call a technician if: E4 persists despite good airflow and a new sensor; the main PCB or refrigeration system may require professional diagnosis.