This paper describes the engineering effort and method of manufacture used to build 36 high efficiency, automatic defrosting refrigerator-freezers. This work was undertaken as Phase II of a Department of Energy sponsored project to develop and test market a refrigerator-freezer of the automatic defrosting type that represented the best current capability for energy efficiency. A national laboratory was the prime contractor for the project, with a research firm and a manufacturer serving as subcontractors for the research and development, design engineering, and manufacturing phases of the task.