Should the Rearview Mirror Heating Use Hot or Cold Air?
3 Answers
The rearview mirror heating shares the function with the rear window defogger and does not require turning on cold or hot air. The function of rearview mirror heating: The rearview mirror heating function refers to the ability of the exterior rearview mirrors to be heated by electric heating wires embedded behind the mirror surfaces when driving in rainy, snowy, or foggy weather, ensuring the mirror surfaces remain clear. The principle of rearview mirror heating: The working principle of electrically heated rearview mirrors is very simple and not highly costly. It involves installing an electric heating element (heating film) inside the mirror surfaces of both rearview mirrors. 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, thereby heating the mirror surfaces to remove fog and frost, providing great convenience for the driver.
I've been driving for over a decade, and the rearview mirror heating function actually operates independently of the air conditioning system. You don't need to turn on the hot or cold air to use it. The rearview mirror itself has a dedicated heating button, usually located on the control panel to the left of the driver. Pressing it automatically heats the mirror surface to melt frost or clear fog. This feature is extremely practical, especially when driving in rainy weather or on winter mornings, as it quickly improves visibility clarity—it has nothing to do with the air blowing inside the car. Some people think turning on the hot air from the AC can indirectly heat the mirror, but that's a completely different system: the AC airflow only circulates inside the car, while the heating function relies on a layer of heating wires inside the mirror. I remember the first time I used it on a foggy day—my visibility instantly improved, making driving much safer. During every maintenance check, I make sure to test this button to ensure it works properly when needed most.
As a new driver who just got my license, I also used to wonder whether to turn on the air conditioning for the rearview mirror heating. But actually, it's unnecessary. The rearview mirror heating is an independent function controlled by a button in the car, usually located near the rearview mirror or on the left side of the steering wheel. Pressing it will automatically heat and defog the mirror, unaffected by hot or cold air. Last time I drove in the rain, the mirror was covered with water droplets, but after pressing the heating button, it cleared up within minutes—super convenient. Don’t make the same mistake I did initially by trying to use the air conditioning; it only makes the cabin uncomfortable and wastes fuel. Modern cars basically all have this design—simple and safe to operate. If you encounter similar issues, just check the owner’s manual.
