Penerapan Metode TOPSIS pada Sistem Pendukung Keputusan Kelayakan Pembelian Unit AC Bekas Berbasis Web

CV Ziyad Aircond Indonesia determines the feasibility of used air-conditioning (AC) units manually, relying on technician experience without a standardized assessment procedure. This may lead to inconsistent assessments and suboptimal purchasing decisions. This study develops a web-based decision support system using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. Data were collected through observation, interviews, and literature study, while the system was developed using the Prototype model. Six criteria were applied: compressor condition (weight 0.20), evaporator condition (0.15), condenser condition (0.15), unit age (0.15), brand (0.15), and price (0.20). TOPSIS processing includes decision matrix normalization, weighting, positive and negative ideal solutions, distance calculation, preference values, and ranking. The calculation used ten used AC units with the same cooling capacity. AC010 achieved the highest preference value of 0.7393, followed by AC003 (0.6633) and AC001 (0.6418), while AC007 ranked last with 0.3556. Functional testing reported that tested features worked as expected, and user evaluation reached an overall score of 84.44%, categorized as very good in the thesis. The system provides structured recommendations to support, rather than replace, the company’s final purchasing decision.