If your Daikin air conditioner is not cooling effectively, there could be a few possible reasons. Firstly, check if the air filters are clean and not obstructed, as this can reduce airflow. Additionally, check if the temperature setting is too high or if the unit is in energy-saving mode, as this can affect cooling performance. If the issue persists, it could be a sign of a refrigerant leak or a malfunctioning component, in which case you should contact a licensed technician for repairs.