How does the blower work on VW?
On Beetles from '49 through '74, that metal shroud in the very
rear of the engine has a fan in it, driven by the generator, which
of course is driven by the belt in the front of the engine. As the
fan turns, it drives air through the ducts on either side, and
cools the engine. It also pushes air through the heater boxes that
heat the cab of the car.