04 gto looses radio signal

hey guys i got an 04 gto with a kenwood radio evry time you turn on the rear defrost the radio gets alot of interference alot of static any clus to what it might be

You have a break in one or more of the rear defogger grid lines. There are repair kits available at most auto supply stores to repair the breaks. The hardest part is finding them. If you can get the rear window foggy, turn on the rear defroster and watch the areas that don't clear as fast as the rest of the window. That is where the break is located. The breaks may not be very big but this is what causes the noise. It will only appear while listening to the radio and mostly on FM.sparky