Rahmawati, I. and Wibisono, D. 2025. Proposed Improvements of Air Conditioner Preventive Maintenance In The Coal Mining Industry By Utilizing DMAIC Methodology . Dinasti International Journal of Education Management and Social Science. 7, 1 (Nov. 2025), 1073–1086. DOI:https://doi.org/10.38035/dijemss.v7i1.5555.