LOADED UP MY 6 YEAR OLD SON AND 3 YEAR OLD DAUGHTER IN CARSEATS IN THE REAR OF A 4 DOOR F150. STARTED VEHICLE TURNED ON REAR DEFROST. WITHIN 30 SECONDS, THE REAR CORNER BEHIND MY CHILD'S SEAT STARTED TO SMOKE. 30 SECONDS MORE AND THE ENTIRE BACK WINDOW SHATTERED. NOT ONLY WAS THIS VERY DANGEROUS WITH TWO YOUNG CHILDREN IN THE BACK SEAT, IT WAS VERY TRAUMATIC FOR THEM