The system is also designed with efficiency in mind. Many vehicles automatically switch the rear defroster off after a certain amount of time. This prevents unnecessary electrical demand and reduces the strain placed on the battery and alternator, especially during extremely cold weather.
However, those thin lines are surprisingly delicate. A metal ice scraper, abrasive cleaning pad, or sharp object can scratch or break one of the conductive strips. Even loading large items into the trunk carelessly can damage the lower portion of the grid.
Once a strip is damaged, that section may stop heating properly, leaving a small area of frost or fog behind. If several lines are broken, the problem can become much more noticeable and potentially reduce visibility when driving in difficult weather.
