The answer to 'ductless system making noise' is that there are several common causes for a noisy ductless HVAC system, including issues with the compressor, fan, or refrigerant lines. Symptoms can include grinding, rattling, or whistling sounds. Some solutions may involve tightening loose parts, replacing worn components, or adjusting refrigerant levels.
If the noise is persistent or accompanied by other issues like reduced airflow or poor cooling performance, it's best to call in a professional HVAC technician to diagnose and repair the problem. Attempting DIY repairs on a ductless system can be risky and may void the warranty, so it's generally recommended to have a qualified technician handle any major repairs or maintenance.