extruder fans

[anthony27]

Hi Guys, me again!
I have noticed when I crank up my machine, and heat the extruders, their respective fans are definitely not spinning!
in fact I cannot remember them ever spinning, which is a bit of a worry , is it a maker ware issue do you think, or a hardware issue?
I am assuming if they don't spin, something will overheat? maybe this is why there are filament jams and blockages?
Also I may just go and purchase some new ones locally, i am away from my machine, what size do I need?
is there a way to manually test them?
many thanks for all your help in advance