The thesis was written to present an AC-filling machine renewal project in automotive industry. It is based on a project the author managed at Valmet Automotive manufacturing engineering department. During the project, an older filling machine was relocated from the assembly rework station to the production main line, and the rework station received a new filling machine. The subject was chosen, because it involved the author's studies in environmental engineering and because it was a part of his everyday work. As a result of the project, the production department could handle the increased volume of vehicles requiring refrigerant R-1234yf filling. In this thesis, following subjects are presented: Valmet Automotive as a company and their products, theory of refrigeration process in general, as applied in automotive industry and refrigerants used in the industry. Thesis also covers the actual project and its different phases.