This is one of the article on instructables that caught my eyes yesterday.  California has gotten very hot lately to the point where we are getting 100 degree days.  Even though air condition still works for my car, it would really suck for those people whose AC is broken during this time of the year.  As an alternative to fix it in the body shop (which will cost a couple hundreds of dollars or more), it will be more economical and more tolerable if there is a self made fan like the one pictured above!