Display shows Lt and the unit stops or will not start cooling in low ambient temperature conditions.

Note: Many De'Longhi portable and window units will not cool if the room is below a certain temperature (often around 18°C / 64°F).

• 1. Verify room temperature: Use a separate thermometer to confirm the room is within the operating range listed in the user manual. If the room is too cold, switch to FAN mode or use HEAT mode (if available) instead of COOL.
• 2. Improve airflow: Clean the front and rear filters, ensure supply and return grilles are not blocked by curtains, furniture, or covers.
• 3. Defrost cycle: Turn the unit OFF for 30 minutes to allow any ice on the evaporator to melt. Place towels under the unit if you suspect internal ice melt.
• 4. Sensor check (advanced): If Lt appears even in a warm room, the evaporator temperature sensor (NTC) may be faulty. Access the sensor near the evaporator coil, inspect for dislodged or damaged wiring, and test resistance against the service manual chart.

If Lt persists in normal room temperatures and airflow is good, contact a technician to test the sensor and control board.