Diagnosis
The compressor is running but the evaporator coil is not getting cold enough. This is usually due to a refrigerant leak or a failed compressor. The fan may blow air, but no condensation forms.
How to Fix It
First, confirm the ambient room temperature. This unit requires a minimum temperature of 41°F (5°C) to operate effectively. If the room is colder, it will not dehumidify. Ensure the unit is set to 'Continuous' mode and the humidity set point is below the current room humidity (e.g., set to 45% if room is at 60%).
If That Didn't Work
Check the air filter. A completely clogged filter restricts airflow over the cold coil, preventing condensation. Remove, clean with warm water, let dry completely, and reinstall.
Heads Up
In a very dry environment (below 30% RH), the unit may run without collecting visible water. This is normal operation, not a malfunction.