The answer to 'why is my dehumidifier not cooling' is that there are several common causes, including a refrigerant leak, a problem with the compressor, or a clogged air filter. Symptoms may include the dehumidifier not getting as cold as it should, the air coming out feeling warm, or the unit not removing moisture effectively.
If your dehumidifier is not cooling properly, the first thing to check is the air filter. A clogged filter can restrict airflow and cause the unit to work less efficiently. You can try cleaning or replacing the filter yourself. If that doesn't solve the issue, it's likely a more complex problem that will require a professional HVAC technician to diagnose and repair, such as a refrigerant leak or compressor failure.