DIAGNOSIS The compressor is running but the coils aren't getting cold enough to condense moisture. This is usually an environmental issue, not a machine failure.
FIX Check the room temperature first. These units have a rated operating range, typically above 65°F (18°C). If the room is colder than that, it physically cannot extract moisture efficiently. Move it to a warmer room or raise the ambient temperature.
IF THAT DIDN'T WORK The air filter is clogged, starving the evaporator coil of airflow. Power off, unplug, pull the filter from the back, and rinse it under cool water until it's clean. Let it dry COMPLETELY before reinstalling. A damp filter blocks more air.
HEADS UP Don't confuse 'running' with 'working.' Listen for the fan AND the deeper hum of the compressor. If you only hear the fan, the compressor might not have kicked in due to a delay or fault—wait 5 minutes. If only the fan runs, that's a different problem.