i've had air con on my sierra/granadas for the past 8 years
i've never seen the fans spinning in all that time, even the ones that aren't siezed at least 3 of them wern't and they wern't sized either
not that i'm siang they don't, i'm just saying i have't had one thats come on

i've seen them spinning on bmw's and rollers though,s o perhaps they should