Why Front Windshields Don’t Have Electrical Defrosters Like Rear Windows

Who doesn’t love flipping a switch on the dashboard and having the frost on the rear window magically disappear? Have you ever wondered why the front windshield doesn’t have the same system? It turns out that unlike the rear window, it’s easy to route hot air to the front window, and hot air has three advantages over defrost wires: (1) it doesn’t impair vision and distract drivers the way wires would; (2) it removes interior moisture and fog faster, in addition to melting ice on the outside; and (3) it heats and ventilates the cabin with warm fresh air. While certain car manufacturers experimented with metal films on the front windshield that heated up and worked like defrosting wires, they dropped the project when the cost became prohibitive. In addition, they discovered that the film tended to discolor and de-laminate over time. Finally, research has shown that the metal defrosting film on the front windshield also renders things like radar detectors and dash cams inoperable, and impairs cell phone reception.