Important reason why some cars have lines on the rear window might surprise you

Most features on a car have an obvious function, but there’s always something that some people just have no idea what it’s for.

Although I’m pretty sure some people have no idea how to use their indicators, I’m actually talking about the thin lines that some cars have across the rear window.

You might think they actually have no use at all but it isn’t a design choice, there’s an important reason why cars have those lines and it might surprise you.

The lines are actually a very clever design (anmbph/Getty Images)

So, what are the lines?

It might seem like it’s something that could actually prove to be a hindrance while driving or something that has the potential to obstruct your view but they’re actually a very clever design.

The lines act as a frost clearer for when the cold weather hits.

They are actually small wires that are squished between the two glass layers and, when an electrical current is sent through them, it generates heat.

This clears the frost that fogs up the rear window, making it easier to see out the back.

What happens when it doesn’t work?

There might be times when the defroster in the rear window lets you down and you might have to resort to sorting out the frost the old fashioned way — a flimsy scraper and brute force.

But why isn’t the function working properly? There’s a few different reasons.

If you’ve been using the defroster a lot and it’s suddenly stopped working then it might be worth checking to see if the fuse has blown.

Luckily, if this is the case then it’s a pretty simple fix of just replacing the fuse for a new one.

The lines act as a defroster for the rear window (shunli zhao/Getty Images)

However, if the fuse looks fine then it might be that there’s an issue with the grid.

A common problem that people find is when the lines have been applied directly to the surface of the glass.

This means they’re vulnerable to damage and this can stop them from generating the heat needed to clear up frost.

If you’re quite handy, this issue can be resolved with a DIY kit but if not, it might mean a call to professionals is needed to repair the problem.

Last but not least, another issue you might face is that the button to activate the defroster has stopped working.

There’s nothing actually wrong with the lines themselves but just that the electrics in the button aren’t working properly.

In this case, you’ll probably need the help of a mechanic to get it back into working order.