Encoding capacitor replacement rules as code for HVAC part validation

Many e-commerce fit questions for commodity electrical parts are answered with lookup tables, which break down when thousands of part numbers reduce to a few ratings. The article proposes encoding substitution rules and checking candidates against the original part instead. For HVAC run capacitors, the key rules are that microfarad ratings must match exactly, voltage must be equal or higher, and the capacitor type must match, while shape only affects bracket fit. The author shares a small Python validator that returns reasons for mismatches, separates hard failures from warnings, and normalizes label formats. The same pattern could apply to contactors, transformers, and air filters.