How to Activate the Rearview Mirror Heating Function?
4 Answers
To activate the rearview mirror heating function, simply press the rear window defogger button located on the central console's air conditioning panel. This will simultaneously activate both the rear window defogger and the rearview mirror heating function. The rearview mirror heating function refers to the ability of the rearview mirror to be heated by electric heating wires embedded behind the mirror surface when driving in rainy, snowy, or foggy conditions, ensuring a clear view of the mirror surface. Rearview mirrors can be classified as follows: 1. By installation position: interior rearview mirror, exterior rearview mirror, and under-mirror; 2. By mirror surface shape: flat mirror, spherical mirror, and double-curvature mirror. The field of view of a rearview mirror is determined by: 1. The distance between the eyes and the rearview mirror; 2. The effective area of the rearview mirror; 3. The radius of curvature of the rearview mirror; 4. The tilt angle of the rearview mirror relative to the line of sight; 5. The distance between the rearview mirror and the ground.
I've driven about ten different cars, and the rearview mirror heating switch is actually hidden in all sorts of places. The most common is the button on the air conditioning panel with a rectangular frame and wavy arrows, and many share the same button with the rear window heating. Some cars are even more discreet—you have to turn the mirror adjustment knob to the heating icon position to activate it. Once, when driving a friend's BMW, I had to dig through three layers of menus on the central screen just to find the heating option! My advice is to turn it on immediately after a cold start, and for rainy days, activate it five minutes before setting off for the best effect. But remember, this feature is mainly for defrosting, not removing raindrops—during heavy rain, you’ll still need to wipe the windows.
Last week, while teaching my novice neighbor how to use the car, I realized many people don't know what the rearview mirror heating button looks like. Look to the left of the steering wheel for a rectangular icon with three upward wavy lines—that's the one. Press it, and the indicator light should turn on. Here are two veteran driver tips: First, the heating only activates below 15°C, so pressing it in summer won't do anything. Second, some cars automatically turn it off after 20 minutes to prevent battery drain. Once, while renting a car, I encountered a stuck button—forcing it could blow a fuse. In such cases, simply turning on the air conditioner's defog mode can activate the heating instead.
Rearview mirror heating shouldn't be a hidden feature! Driving in heavy rain yesterday, I only remembered this function when the mirrors became too blurry to see. Most cars have a heating button with a thermal symbol on the driver's door panel or center console, while luxury vehicles might integrate it into the climate menu. Tests show that in gasoline cars, the mirrors become warm within 5 minutes of activation, and even faster in electric vehicles. An easily overlooked point: modified mirror lenses or anti-glare films may affect heating efficiency. In winter, avoid scraping ice with hard objects; instead, use the heating function along with defogging air conditioning for a time-saving and safe solution.
