ok so weirdest thing my buddies rear window defrost doesnt work.. checked mine.. works perfect.. on a cold day we turn his on it will stay on for the 15 min span and the light turns off but nothing is actually happening on the rear window. now im thinking that the wires that hookup to the window...

I have a 2002 330Ci. I purchased it used, so I do not have the owners manual to look this issue up. When the tempurature drops below 37 degrees F, when I turn the car on, the rear defrost is automatically turned on. 1.) is that normal? 2.) is that okay? I have tint, so I don't need to...