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

Safety first: Disconnect power before servicing. Allow any ice on the coil to melt before touching components.

Steps to address E4:

• Check ambient conditions: Ensure the dehumidifier is used within the specified temperature range (typically 41–95°F / 5–35°C). Operating in very cold rooms can trigger defrost errors.
• Inspect air filter and grilles: Remove and clean the air filter with mild soap and water. Make sure intake and exhaust grilles are not blocked by walls, curtains, or dust.
• Verify fan operation: Turn the unit on and observe the fan. If it does not start or runs slowly, inspect the fan motor and capacitor (if equipped). Replace the fan motor if seized or noisy.
• Check evaporator sensor: Confirm the evaporator temperature sensor is properly attached and not damaged (see E3 procedure). A faulty sensor can misreport coil temperature and cause defrost errors.
• Defrost the coil: If the evaporator is heavily iced, unplug the unit and allow it to thaw completely. Do not chip ice with sharp tools. After thawing, restart and monitor.
• Control board replacement: If airflow is good, sensors are OK, and E4 persists, the defrost control logic on the main PCB may be defective and require replacement.

Warning: Do not operate the unit with covers removed; this can cause improper airflow and further icing.