Dehumidifier beeps and displays E4, fan may still run but compressor is off

Safety: Unplug the unit before removing covers. Do not attempt to open the sealed refrigeration system yourself.

Basic checks:

• Allow defrost: Turn the unit off and let it sit unplugged for at least 1–2 hours to fully defrost any ice on the evaporator. Restart and see if E4 returns.
• Clean filters and grilles: Remove and wash the air filter with mild detergent, dry completely, and reinstall. Vacuum dust from intake and exhaust grilles to restore airflow.
• Check room conditions: Ensure the unit is used within the specified temperature range (typically 5–32°C). Very low room temperatures can trigger E4.

Advanced checks (for competent DIYers):

• Inspect evaporator: With the cover removed, check if the evaporator coil ices up quickly when the unit runs. Heavy icing may indicate airflow problems or low refrigerant.
• Verify evaporator sensor: Follow the E2 procedure to test the evaporator NTC sensor. Replace if readings are abnormal.
• Refrigerant issues: If the coil only partially frosts or does not get cold at all, the sealed system may be low on refrigerant or have a compressor issue. This requires an F‑Gas certified refrigeration technician; do not attempt to recharge yourself.

If cleaning filters and confirming proper room temperature do not clear E4, and the sensor tests good, contact a professional for sealed system diagnosis.