Do you know if it is an *electronic* switch? Or, a mechanical one?
[Hint: if it is a sexxy "touch activated" thing, it is electronic;
if it has some heavy *feel* to it -- like an old fashioned light
switch -- it is mechanical. More or less.]
An electronic switch isn't really controlling anything. Instead,
it simply CONVEYS YOUR WISHES to something else (controller) that
actually does the switching. So, if that "something" decides,
rightly or wrongly, to turn the fan on (perhaps because it senses
the range is still hot and it wants to cool it?), then it can.
A mechanical switch can't (usually) flip from the off POSITION
to the on POSITION without some external force activating it.