Why is the left side of the Corolla's rearview mirror heating hotter than the right side?
3 Answers
Because the heating wire in the rearview mirror is damaged, it can only be repaired at a professional 4S shop. The rearview mirror heating function refers to the heating of the mirror surface through the electric heating wire embedded behind the lens when driving in rainy, snowy, or foggy weather, ensuring the clarity of the mirror surface. Rearview mirror heating switch: The rearview mirror heating symbol is a pattern of three curved upward arrows combined with a rectangle. The position of the rearview mirror heating switch varies among different car models, but the symbols are generally similar. There are two designs for the rearview mirror heating control switch: one is integrated with the electric rearview mirror adjustment combination switch, and the other is located on the air conditioning control panel, both serving the same purpose. Principle of rearview mirror heating: After pressing the rearview mirror heating button, the electric heating pad behind the rearview mirror glass will quickly heat up to a fixed temperature within a few minutes, usually between 35 to 60 degrees Celsius. Hot air will emerge from both left and right rearview mirrors, and the water droplets on the mirror surface will gradually evaporate and shrink due to the rising temperature, while the fog will slowly disappear, achieving the effect of defogging and defrosting.
It's actually quite common for the left side of the Corolla's rearview mirror heating to be hotter than the right. At first glance, I can tell it's likely an issue with the heating element or the circuit. The left side being hotter might be due to aging heating components on that side—long-term vibration and rainwater corrosion can thin or break the heating wire, causing the right side to not heat up properly. As for the circuit, loose connectors, short circuits, or malfunctioning relays can all lead to uneven current flow. It's best to start with a simple self-check, like turning on the heating function to see if both sides light up simultaneously. If the right side light doesn't turn on or flickers, it's more likely a blown fuse or a faulty control module. The fuse is located in the fuse box under the dashboard—check the manual for the specific model and try replacing it. If the issue persists, head to a professional repair shop immediately—don't delay, as poor visibility during rain or snow poses significant risks. Remember, safety first—avoid tampering with wires yourself to prevent electric shock or worsening the problem.
I get really annoyed when I see this kind of issue with my Corolla's mirror heating. The left side is warm, while the right side stays cold—clearly something's wrong. Most of the time, it's because the heating element on the right side is faulty or has poor contact. Since the left side is closer to the driver, it might be more exposed to dust or moisture, causing the right side to fail over time. I once tried checking it myself—opened the door, located the small plug on the back of the mirror, unplugged and replugged it, but the problem persisted. The fuse is probably fine, but if the temperature difference is too big, a short circuit or unstable voltage might be the real culprit. I’d suggest using the heating function sparingly—only when absolutely necessary—to avoid speeding up wear and tear. If you notice symptoms, just take it straight to the 4S shop. They can run quick tests with their equipment, and it won’t take much time. Don’t underestimate this issue—foggy or icy mirrors in winter can be seriously dangerous.
