How to Defog Windshield? – Foggy Car Windows

It doesn’t matter what kind of climate you live in; keeping your car comfortable can mean battling foggy windows.

Why does my windshield keep fogging up?

Windshield fogging up outside because of condensation when the temperature outside the car is much different than the temperature inside your car. Try to match the temperature inside your car to the outside temperature as closely as possible to reduce or eliminate fog or condensation.

If you live in a cold climate, you’re likely to use your car’s heater to stay warm, which can cause fog to build upon the inside of your windows. However, it’s possible to have the opposite problem in warm, humid climates when you turn on the air conditioning.

How to Defog Windshield?

To defog the windshield when outside is cold, you need to:

  • Turn the heat on to the maximum speed (1 minute)
  • Then turn on the air condition (1 minute)
  • Turn off the recirculation button (30 seconds)
  • Crack the windows and let fresh cold air into the car.

The temperature and moisture content of the air is to blame for foggy windows. Condensation occurs when moist air inside your car hits air below the dew point, a specific temperature. Your car’s windows appear foggy because of condensation. After your AC system has cooled the muggy air outside your car, it reaches the dew point on your windshield on a hot, humid day.

Anytime you can’t see clearly in all directions, whether the fog is inside or outside your windows, it’s potentially dangerous. Knowing how to keep your windows clear in any weather is therefore crucial.

When it’s cold outside, and you turn on your car’s heater, fog usually forms on the inside of the windows. Some options for defogging windows include:

For a quick fix: First, turn up the heat to its highest setting, as hot air can hold more moisture. Then turn on the air conditioner, which will remove moisture from the air as it passes over the cooling coils. As a final step, turn off the recirculation button so colder, dryer air enters the vehicle. To help exchange humid interior air with dryer exterior air, crack your windows for a few minutes.

Car manual recommends turning on the defroster and blowing warm air across the windshield to evaporate the moisture. Then, shut off the recirculation feature on your vehicle’s ventilation system. Then, instead of continuously drawing air from the outside, your car’s heating or cooling system recycles the air already inside the vehicle.

You want your car to continuously draw air from the outside, which is drier, rather than recycling humid air from the inside during cold weather. (Unsure if your vehicle has recirculation? Ask your mechanic. If you can see an arrow going around the dashboard, you’ve found it. A car icon may be featured on occasion.)

How to Defog Windshield when outside is warm?

To defog the windshield when outside is warm, you need to:

  • Use windshield wipers.
  • Set air condition on low or turn off air condition—warm-up car.
  • Turn off the recirculation button (30 seconds)


This occurs when the outside temperature and moisture level are higher than those found inside a vehicle. Changing the temperature in your car to match the outside temperature is similar to changing the temperature in your car when it’s colder outside than it is inside.

In this case, it means warming up the inside. Keep the following tips in mind:

Start by using your windshield wipers to keep your windshield clean. The condensation will be removed as a result of this action until the temperature is balanced. If this doesn’t work, Car manual recommends turning off the air conditioner completely.

Recirculation should be turned off: The recirculation feature of your car should be turned off to combat foggy windows. This will allow the temperature and moisture levels inside your car to match that outside.

How to prevent windshields from fogging?

To prevent a foggy windshield, try the following steps:

  • 1. Use a window cleaner that contains ammonia

Windshield buildup can be removed with the help of an ammonia-based window cleaner. As a result, you can clean the interior of your windshield with a window cleaner containing ammonia. Apply the window cleaner in horizontal or vertical strokes, and reapply it to the interior of your windshield regularly.

  • 2. Apply shaving cream to the interior of your windshield

To remove the shaving cream from your windshield, use a dry, clean towel to wipe the windshield’s interior. As a result, a protective film is formed on the inside of your windshield, which helps to prevent fogging.

  • 3. When you heat your car, turn on the defroster

When you preheat up your car, turn on the defroster. Set the defroster the night before if you’re using a power inverter to warm up your car in the morning.

  • 4. Use the fresh air mode

Make sure your car’s heater or air conditioner is set to fresh air mode and not recirculate. Otherwise, your car may recirculate damp air, which raises the danger of windshield fogging.

  • 5. Keep a car window open

Even keeping one window slightly open in your automobile might help prevent your windshield from fogging up with condensation.

  • 6. Wipe your shoes before you enter your car

You can prevent your windshield from fogging up by keeping even one window slightly open in your automobile.

  • 7. Inspection of your vehicle’s HVAC system

Fog on your windshield might be difficult to clear if your heating, ventilation, and air conditioning (HVAC) system is not working properly. However, when you engage your car’s defroster, you may see that your windshield has fogged up. The technicians at the auto body shop will be able to evaluate the HVAC system of your vehicle and make any necessary repairs.

It is unsafe to drive with a foggy windshield, both for you and for other motorists. You can, however, easily remove a foggy windshield both inside and outside of your vehicle by following the steps listed above.

Robert Aksamit

Robert Aksamit

Robert Aksamit is a mechanical engineer and automotive industry expert. Robert was born in Minnesota and worked in the US automotive industry for 25 years. He is highly regarded for his passion and dedication to continually improving vehicles in response to customer feedback. Robert has a keen eye for sourcing the best vehicle components and materials on the market and is always looking for ways to enhance the user experience. As a writer, Robert covers automotive-related topics. Read more on Robert Aksamit's about page. Contact Robert:

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