Hi ,on my E36 1993, rear windows stuck open and close after few hours or on the next day,is somebody had this problem 

i checked comfort relay for cracks and damages ,but its ok,motor of the windows also is good by them self,where can be the problem?

No problem with front windows,only with both rear

I am not shure,but on my model have only one relay (comfort relay,that operate all four front and rear windows)

Thank you in advance for suggestions!

Morning Evgeni

Welcome to the Forum

Simple things first as rear windows generally get less use try a silicone spray in the runners in case they are sticking

Then try checking www.realoem.com to see if the small exploded drawings help or maybe www.pelicanparts.com look in the articles section they have some brilliant "How Too's" with pictures

Dave