How to Remove Fog in the Car: Quick & Effective Tips

Key Highlights:

• Fog build-up is very uncommon in modern cars that feature automatic climate control.

• Windshield fog formation can also be prevented in cars without AC.

• Regardless of the method used, temperature equalisation on either side of the windshield is the effective end goal.

How Does Windshield Fog Form?

Windshield fog is generally caused by condensation. This occurs when there is a temperature difference between the inside and outside of your vehicle, causing moisture in the air to settle on the glass surface. Such conditions are common during the monsoon or winter months. When the interior of the car is warmer than the outside air, condensation forms on the inside of the windshield. On the other hand, if the air outside is humid and the glass becomes cool due to the air conditioner, fog can develop on the outer surface.

How to Remove Fog From Inside the Windshield

Fog on the inside of the windshield is more common and dangerous. Here’s what you can do about it:

Turn ON Defogger/Defrost mode

Most vehicles feature a defogger button, usually denoted by a windshield icon with wavy arrows. Pressing it activates the HVAC system and directs warm air toward the windshield to lower the humidity on the glass surface. Ensure the airflow is aimed at the windshield and side windows for the best results.

Set the Temperature to Warm

Choose warm or hot air instead of cold, as warmer air can hold more moisture and is more effective at clearing condensation. Begin with a moderate temperature setting and gradually increase it if needed.

Turn ON the Air Conditioning

Although it may seem unexpected, switching ON the AC helps to eliminate moisture from the air inside the car. The air conditioning system works like a dehumidifier. Even when using warm air, keeping the AC ON ensures that the air reaching the windshield remains dry.

Increase Airflow and Open Windows Slightly

Increasing the blower speed improves the airflow throughout the cabin. Opening the windows slightly can help equalise the humidity between the interior and the outside, letting in fresh air and carrying out excess moisture.

Use ‘Recirculation’ Wisely

When clearing fog, it is important to switch OFF the recirculation mode. This feature traps the same air inside the cabin and can increase humidity levels. Allowing fresh air from outside helps replace the moist air inside with drier air.

How to Remove Fog From the Outside of the Windshield

Fog can also form on the exterior of the windshield, particularly in humid conditions. Here’s how to overcome it:

Use Windshield Wipers

If fog appears on the outside of the windshield, using your wipers is the most effective solution. Turn them ON in their lowest setting. Some vehicles also feature automatic wipers that start working when moisture is detected by built-in sensors.

Activate Windshield Washers

When the windshield is dirty or has a layer of grime, moisture tends to stick to it more easily. To prevent this, use windshield washers to clean the glass thoroughly. A clean surface drastically reduces the chances of fog forming.

Adjust the Cabin Temperature Gradually

Try not to create sudden temperature differences inside the car. If the interior is kept too cool while the weather outside is warm and humid, condensation can build up on the outer surface of the windshield. Instead, increase the cabin temperature gradually to minimise this effect.

How Modern Cars Eradicate Windshield Fog

Modern cars are built to manage windshield fogging far more effectively than vehicles from a decade ago. Here are some features that help them do it:

Automatic Climate Control

Most mid-range and premium cars today come equipped with automatic climate control systems that continuously monitor the humidity and temperature inside the cabin. It can make real-time adjustments to airflow and temperature to keep the windshield clear.

Heated Windshields

Certain premium vehicles are equipped with electrically heated windshields (and ORVMs). These windshields contain fine wires embedded in the glass that warm up when switched on, removing fog within seconds. This function is particularly beneficial in cold or damp weather conditions.

Humidity Sensors

When moisture content begins to rise, the system responds by adjusting the airflow or turning on the defogger. This proactive approach helps prevent fog from forming before it even becomes visible.

UV and Infrared Blocking Windshields

These windshields come with special coatings that help control the temperature inside the car. By keeping the interior cooler, the chances of fog formation drop, as the glass does not become significantly warmer than the air outside.

Alternative Methods to Prevent Windshield Fog Without Using AC

Although the air conditioning system is the most efficient way to clear fog, certain other approaches do not need it. These alternatives are particularly helpful for those looking to lower fuel usage or preserve battery power in electric vehicles, in addition to owners of classic cars that do not feature air conditioning.

Keep the Windshield Clean

A clean windshield is far less prone to fogging. When dirt or oily residue is present on the glass, it offers more surface area for moisture to cling to. To prevent this, clean the interior side of your windshield regularly using a high-quality glass cleaner and a microfiber cloth. You can also try a homemade mix of vinegar and water in a spray bottle. This solution not only removes grime but also leaves a thin coating that helps minimise condensation.

Apply Anti-fog Products

There are many anti-fog sprays and wipes available in the market that can be used on the inside of the windshield. These products create a clear coating that helps stop condensation from forming on the glass. Follow the instructions carefully when applying the product and make sure to reapply it every few weeks to maintain its effectiveness.

Improve Cabin Ventilation

Make sure the air vents and cabin filters are clean and free from blockages. A clogged air filter can lower the performance of the ventilation system, leading to moisture remaining inside the car. Changing the cabin air filter regularly can significantly improve this. Whenever you can, leave the windows slightly open while parking to help fresh air circulate, particularly after a rainy day. Damp clothing or umbrellas can introduce moisture into the cabin, which may later result in fogging.

Use Desiccants

Products that absorb moisture, such as silica gel packets or car-specific dehumidifiers, can be placed beneath the seats or on the dashboard. These items help remove excess humidity from the air inside the car. Some drivers also use a sock filled with cat litter as a simple DIY dehumidifier.

Unconventional Approaches

Some drivers rely on unusual yet surprisingly effective techniques. One such method involves using a chalkboard eraser to remove moisture from the glass without leaving streaks. Another approach is to apply a thin layer of shaving foam to the inside of the windshield. This process creates a protective film that helps with moisture formation.

How Can You Start to Make it Stop?

A foggy windshield is more than just a minor inconvenience. It reduces visibility, affects driving safety and adds unnecessary pressure while on the road. Thankfully, both conventional and modern solutions are available to tackle this issue effectively. Using the defogger, the vehicle’s AC system and managing airflow correctly can help clear the windshield in a short time. Modern cars offer added creature comforts such as humidity sensors, heated glass and, at the very basic, automatic climate control.

For those who prefer not to use the AC, regularly cleaning the windshield, applying anti-fog products and improving the ventilation inside the cabin are effective ways to reduce fog build-up. With some basic knowledge and consistent care, you can maintain clear visibility and drive more safely regardless of the weather conditions.

FAQs

1. How can I quickly remove fog from the inside of the windshield?
Activate the defogger setting with warm air, turn on the AC to remove moisture and increase airflow toward the windshield.

2. Is it necessary to use the air conditioner to remove fog?
No, but it helps significantly. You can also defog by using warm air without AC, opening windows slightly or using anti-fog products.

3. Can dirty windshields cause more fog?
Yes. Dust, oil or grime on the glass gives moisture more surface to cling to, making fog worse.

4. Can I prevent fog without using electronics or systems in the car?
You can use anti-fog sprays, keep windows slightly open, clean the glass regularly or use moisture absorbers inside the car.

5. What household items can I use to prevent fogging?
Shaving foam, vinegar and a clean microfiber cloth are common DIY solutions that can help reduce fog build-up.