Diagnosis
The unit is in 'fan only' mode, or there's a refrigerant/low ambient temperature issue. This model has an auto-defrost function that can prevent cooling if it's too cold.
How to Fix It
Check the mode. Make sure you're not set to 'Continuous' or 'Dry' mode with a target humidity that's already been met. Set it to a lower target (like 45%) and 'Dry' mode. Also, ensure the room temperature is above 65°F (18°C). If it's colder than that, the compressor won't cycle on to prevent icing.
If That Didn't Work
There could be a refrigerant leak or a compressor start component failure. Listen closely after turning it on—you should hear a distinct 'click' and a low hum from the compressor after the fan has been running for a minute or two. If you never hear that click-hum sequence, the issue is likely internal.
Heads Up
Yeah, this one's common in basements or garages in cooler months. The specs say it operates down to 41°F, but its efficiency plummets and it will cycle off frequently. It's really designed for warm, damp conditions.