Ductless mini-split systems are split-system units and typically fall under 841510, which explicitly covers both self-contained and split-system window or wall air conditioners. If the configuration does not fit that description — for example, a large commercial multi-zone system — it may fall under 841581 or 841582 depending on whether a reversible heat-pump valve is present.

Parts specifically designed for air conditioning machines and not more specifically provided for elsewhere are classified under 841590. However, general-purpose components such as electric motors, compressors, or copper tubing may be classified under their own headings if they are not dedicated parts. The 'parts' heading applies when the component's principal use is identifiable as serving this heading's machines.