What to Do When the Windshield Fogs Up While Using Air Conditioning in Summer?
4 Answers
The reason for fogging on vehicle windows is due to the significant temperature difference between the interior and exterior under current conditions. Below is an introduction to the causes of vehicle window fogging: 1. Depending on the driving environment, use the front windshield defrosting function to treat the front windshield. 2. If equipped with automatic air conditioning and the option to select vent positions, it is recommended to choose the front windshield and central vent positions, and turn on the rear windshield heating function. This way, the temperature inside the vehicle is constantly regulated, preventing fogging. 3. If it is not possible to select both directions for air outflow simultaneously, turn on the front windshield defrosting function and the rear windshield heating function. 4. If the side windows fog up, you can open the windows slightly to quickly remove the fog. After closing the windows, once the interior temperature rises, fogging will no longer occur.
It's really annoying when the windshield fogs up while using the air conditioning in summer. When dealing with it, I always start with simple methods. Press the defog button on the AC panel—the icon looks like a small fan blade or a fog symbol—this feature is specifically designed to quickly dry the air and remove fog. Then, increase the fan speed to accelerate dehumidification while setting the temperature to a moderate level, not too low (around 25°C), to avoid excessive temperature differences between inside and outside the car that could cause condensation. If the fog is still heavy, I briefly open the windows for a minute or two to let the humid air escape before closing them again. Sometimes, I also use warm air to blow on the glass to speed up fog evaporation. For regular maintenance, I clean the AC vents to prevent dust buildup from affecting dehumidification and check if the filters are clogged, replacing them periodically to keep the system efficient. On hot days, I make it a habit to start the car and turn on recirculation for a few minutes before driving to prevent fogging issues. Safety is always the top priority—don’t wait until the fog gets bad to deal with it.
The root cause of fogging is the condensation that occurs when warm air outside the vehicle meets the cooler glass inside, especially in summer when humidity is high, making the problem more likely to occur. I use the air conditioning's cooling and dehumidification function, with the key being to activate the recirculation mode. This draws the humid air inside the car into the compressor, turning it into dry, cool air before blowing it back out. The vent direction should be adjusted downward as much as possible, avoiding direct airflow onto the glass to prevent the cold air from rapidly encountering heat and worsening condensation. At the same time, ensure the air conditioning system is functioning properly, such as having sufficient refrigerant (Freon) and no leaks, otherwise, the dehumidification capability will be insufficient, leading to frequent fogging. I also check the vent pipes for blockages or aging to avoid poor ventilation. On hot days, I pre-cool the interior environment before driving to reduce temperature differences. Related aspects, such as air quality management, involve using activated carbon filters to adsorb odors, which can also reduce excess moisture accumulation, ensuring clear driving visibility and safety is very important.
Front windshield fogging directly affects driving safety, and I never take it lightly. At the first sign of fogging, I immediately press the defog button to let strong airflow dry the air and remove the fog. If the effect is unsatisfactory, I reduce speed and pull over if necessary, using warm air to completely dissipate the fog. For prevention, I keep the windows clean and use anti-fog coating sprays to reduce water droplet adhesion. When using the air conditioning, I activate the cooling and dehumidification modes, with internal circulation to quickly reduce humidity inside the car. I avoid placing wet items such as umbrellas or clothes in the car and perform regular air conditioning maintenance, cleaning the filter every quarter to maintain efficiency. Never wipe the fog with hands while driving, as it distracts attention. Safe driving is the top priority.
