It's worth noting that the very earliest electric refrigerators had a separate condensing unit outside; see this interesting 1920s Frigidaire training video for

It's worth noting that the very earliest electric refrigerators had a separate condensing unit outside; see this interesting 1920s Frigidaire training video for an example of what that was like: https://www.youtube.com/watch?v=W-t7DqOAMME https://www.youtube.com/watch?v=W-t7DqOAMME There were also centralised systems for apartments where one condensing unit supplied many evaporators in the refrigerator in each suite.