Dehumidifier shows E3 and stops dehumidifying; compressor does not start.

Safety: Unplug the dehumidifier before opening the control panel or front cover.

Steps:

• Check for simple reset: Disconnect power for 10 minutes, then reconnect. If E3 returns immediately, proceed with inspection.
• Locate humidity sensor: On many Trotec units, the RH sensor is mounted behind the front grille or near the air intake, often on a small daughter board or as a small plastic module with vents.
• Inspect for contamination: Dust, lint, or water droplets on the sensor can cause errors. Gently blow off dust with dry compressed air. Do not use liquid cleaners directly on the sensor element.
• Check wiring: Ensure the sensor cable is intact and firmly connected to the main PCB. Look for corrosion on the connector pins and clean with contact cleaner if needed.
• Replace sensor module: If E3 persists and the sensor shows visible damage or corrosion, replace the humidity sensor module with a compatible Trotec part.
• Control board check: If a new sensor does not clear E3, the main PCB may not be reading the sensor correctly and will likely need replacement by a professional.