If the blade is symmetrical, it can be either/or, just inverting the polarity will make it a blower or a puller.
if the blade is snot symmetrical, obviously the black cable is the negative pole, no? (so the blue is the positive). So if you plug it this way to a car battery:
- if the the fan vacuums the air from the curved face and blows it through the flat face, it is a blower,
- it if vacuums the air from the flat face and blows it to through the curved face, it is a puller.
