Rear Window Defrosters don't work

welcome!
try some rainx pretreatment or some such, this is a known prime design defect.

 

The very first post from a new member exclaiming a message of danger is a big red flag... especially when the tags for this thread are taken into consideration. It fits the pattern of a troll, so understand why it is getting called out.

As for the message itself, what is the basis of such a claim? Those of us who experienced winter last year (like my wife and I, each in our own Prime in Minnesota) didn't have any trouble. Accumulating snow melted just fine. Completely covered is a rather odd statement too. At a minimum, the humps in the glass will clear themselves off from the air push.

Where do you live? Not having a brush available will catch some in more mild states off guard.