DIAGNOSIS If it's blowing air but not condensing water, the refrigerant system isn't working. The most common culprits are either a frozen evaporator coil (because it's too cold in the room) or a more serious refrigerant leak.
FIX First, turn it off and unplug it. Open the front grille and look at the cold coil (the one with the fins). If it's a solid block of ice, let it thaw completely for 12-24 hours. Make sure the air filter is clean and the room temp is above 65°F. Plug it back in and set it to a higher humidity target (like 60%) so it doesn't over-cool the coil.
IF THAT DIDN'T WORK If the coil never gets cold to the touch after thawing and running for an hour, the compressor might not be engaging or the refrigerant has leaked out. That's a sealed system repair, which is rarely economical.
HEADS UP Running it in a cool basement (below 65°F) is a classic way to freeze the coil. These are designed for warmer, humid conditions. If you need it for a cold space, you need a model specifically with a 'low-temperature' operation mode.