Dehumidifier displays E4 and stops running; may occur after long operation or in very cold rooms.

Safety first: Unplug the unit before inspection. Do not attempt sealed system (refrigerant) repairs unless you are EPA-certified.

• Check room conditions: Ensure the dehumidifier is used in a room above the minimum operating temperature (typically 41–45°F / 5–7°C). Operating below this can trigger E4.
• Inspect airflow: Remove and clean the air filter with mild soap and water. Let it dry completely before reinstalling. Check that intake and exhaust grilles are not blocked by walls, curtains, or furniture.
• Inspect the evaporator coil: Remove the front panel and look at the coil. If it is heavily iced over, allow the unit to thaw completely (leave unplugged for several hours). Once thawed, clean dust from the coil fins with a soft brush or vacuum.
• Check the evaporator sensor: Ensure the coil thermistor is firmly attached to the coil and wiring is intact. A loose sensor can misread temperature and trigger E4.
• Test operation: After cleaning and thawing, plug the unit back in and run it in a warmer room. If E4 returns quickly and the coil does not frost evenly, there may be a sealed system issue (low refrigerant, compressor problem) or a faulty control board.
• When to call a technician: If airflow is good and the sensor is secure but E4 persists, contact a qualified technician to check refrigerant pressures and the main PCB. Do not attempt to open the sealed system yourself.