Dehumidifier displays E4 and shuts down; may occur after running for some time.

Safety: Unplug the unit. Do not attempt to open the sealed refrigeration system yourself; refrigerant work must be done by a certified technician.

Steps:

• Clean air filter and grilles: Remove and wash the air filter with mild soap and water. Ensure both intake and exhaust grilles are free of dust and obstructions.
• Check room conditions: Very low ambient temperatures can cause frequent defrosting. Ensure the unit is used within the specified temperature range in the Trotec manual.
• Inspect evaporator: Remove the cover and visually inspect the evaporator coil. Heavy ice buildup indicates defrost or refrigerant issues.
• Verify fan operation: Run the unit (with covers reinstalled) and confirm that the fan runs at normal speed. A weak or non-running fan can cause coil freeze and trigger E4.
• Sensor check: Confirm the evaporator NTC sensor is properly attached and reading correctly (see E2 procedure). A faulty sensor can falsely signal freeze conditions.
• Call a technician for refrigerant issues: If airflow and sensors are fine but the coil ices quickly or E4 persists, the system may be low on refrigerant or have a restriction. Contact an HVAC/refrigeration technician authorized for Trotec units.