Why is the defogger not working?
2 Answers
The reason for fogging on the car windshield is due to the temperature difference between the inside and outside of the car and air humidity. If the air conditioning doesn't work, it means the direction of the air vent blowing on the glass is incorrect or not turned on. Here is relevant information: 1. Solutions: Turn on the cooling to lower the interior air temperature to match the outside; turn on the heating to equalize the glass temperature with the interior. Therefore, theoretically, you can turn on the cold air conditioning or open the windows to lower the interior temperature for defogging; you can also turn on the hot air conditioning to blow on the glass to reduce its temperature for defogging. 2. Car windshield: The development of modern car designs is closely related to advancements in glass technology. Over 40 years ago, single-piece curved windshields were already being used in cars, gradually replacing flat windshields.
I've been driving for most of my life, and there are many common reasons why defogging doesn't work. The most common is an aging fan motor that can't turn, preventing air from blowing out; or blocked ventilation ducts with accumulated dust and leaves obstructing airflow. Sometimes, the air conditioning system isn't working, and the dehumidification function fails, causing fog to linger. There's also the issue of temperature settings—turning the heat up too high can actually cause the glass to fog up quickly. When I was younger, these situations often occurred due to older cars with poor maintenance. Later, I found that regularly cleaning the air filter could reduce such problems. Car defogging is crucial for driving safety, especially in rainy or snowy weather when visibility is poor—it's very dangerous. At the first sign of trouble, take your car to a professional repair shop for a full inspection—don't delay. A mechanic once taught me that you can use a dry cloth to wipe the glass as a temporary fix, but the real solution lies in proper repairs.
