The blower fan runs off the mains, using the
transformer primary winding
as an autotransformer on 230V mains. And it's on the 'hot' end of the
winding, so the fan motor's insulation has to withstand the full 230V.
Sometimes they don't and you get insulation breakdown. This starts as
sparka inaisw rhw motor, then the darn thing catches fire. Had to replace
a couple of those over the years...
Hehe, I know that effect.. But no flames. Only sparks and a giving up
motor...
-- Ph