What is the working principle of heated rearview mirrors?
2 Answers
Here is the working principle of heated rearview mirrors: The working principle of electrically heated rearview mirrors is very simple. It involves installing an electric heating element (heating film) inside the mirror lenses on both sides. During rainy or snowy weather, when the driver activates the rearview mirror heating function, the heating element quickly heats up to a fixed temperature within a few minutes, typically between 35-60 degrees Celsius. This helps to heat the mirror surface, removing fog and frost, providing great convenience for the driver. Extension: Heated rearview mirrors are generally more practical in winter. In winter mornings, we often find frost on almost all the car's windows, which is difficult to wipe off with a towel. For the frost on the front windshield, we can turn on the heater to blow warm air onto the glass after starting the car to remove it. The frost on the rear windshield can be removed by turning on the rear window heating switch, which activates the heating wires embedded in the rear window glass.
As a car enthusiast, I always enjoy taking things apart to study them. The rearview mirror heating function is actually quite simple—it basically works by using built-in heating wires to generate heat when electricity passes through. When you press the heating button in the car, the system sends an electric current to the inside of the rearview mirror glass, where a metal mesh or thin-film resistor is embedded. As the current flows through, it generates heat, similar to how an electric blanket works, melting away fog and frost. This technology evolved from the defrosting lines used on car windshields. Nowadays, many vehicles integrate it into the central control system, automatically activating it during rainy or foggy weather for hassle-free convenience. The key is ensuring the circuit functions properly—if the heating stops working, it’s often due to a blown fuse or a faulty relay. If checking it yourself seems too troublesome, just leave it to a mechanic. Overall, this feature makes driving safer, especially in snowy winter conditions, sparing you the hassle of wiping the mirrors with a towel.
