this could be a loose connection which is behind the trim up the side of the window.It can also be a faulty heated windscreen in which case you will need a new one fitting!
Steve
October 2010
I can answer this question...
How can I fix my windscreen defroster on ford galaxy 2.3 (02 Model)?
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.