Defroster Button in Your Car: Uses & More

How to Use the Defroster Button in a Car

Turn on your car and press the defroster button. The defroster button will usually be located somewhere on your dashboard, though it's different in every car. In the majority of vehicles, the button contains a symbol that looks like a curved window with three upward-pointing, squiggly arrows going through the center. Simply press the button and make sure that it’s on by checking to see if it’s lit up.

Press the rear defroster button if needed. Your back window can get just as foggy and icy as the front! If your entire view out of the rear window is obstructed by condensation or ice, you'll know it's time to push that rear defroster button. The rear defroster button is typically found right next to the front defroster button. The two look very similar, except the rear defroster appears as a rectangle with three upward arrows in the middle.

Set the heat and fan speed on high. Condensation on a windshield is a very scientific process, but basically, when the air inside your car is humid, the cool surface of the glass causes that moisture to condense into tiny water droplets on the windows and windshield. Heat is what combats this, so turn the heater and the fan to their maximum settings. Directing this warm air flow at the windshield and front windows will help evaporate the excess moisture on the glass.

Turn on the A/C. Turning on the air conditioning (A/C) after cranking up the heater may seem a bit backwards, but it actually activates a setting on the A/C system that aids in drying the interior air faster by pulling out moisture. While you can defrost your car without using the A/C, using the A/C together with the heater is the quickest way to effectively defog and defrost. If you’re simply defogging your car and not defrosting it, you can stop at this step and wait for the condensation to clear from your windshield. If defrosting, continue to the next step.

Press the air recirculation button and slightly crack the windows if it’s cold out. To quickly dry the saturated air inside your car, allow fresh, dry winter air to enter the inside. Cold winter air holds less moisture, so introducing it will help remove excess humidity from the interior more efficiently.

Use a deicing solution if there’s frost. To clear excessive snow and ice after the defroster button has already been running, use a store-bought deicer or make a homemade solution of 2/3 cup of isopropyl or rubbing alcohol and 1/3 cup of water. Pour the mixture into a spray bottle. The solution will not freeze as rubbing alcohol has a freezing point of -138 degrees Fahrenheit, allowing you to easily spray away windshield ice and keep it in your car throughout the winter for convenience.

Types of Defroster Buttons in Cars

Front defroster The front defroster button in your car can usually be found on the dashboard. The front defroster is controlled through the vehicle's heating and ventilation system. Windshield defrosters direct air from the HVAC system onto the windshield through vents at the front of the dashboard. Most vehicles offer a dedicated defrost mode that channels all airflow to the windshield for maximum defrosting. Drivers can also adjust the temperature and fan speed for the defroster. During winter, using the defrost mode with a high-temperature setting accomplishes two key functions: it defogs the windshield and melts frost/snow, making it easier to scrape the glass and preventing ice buildup while driving.

Rear defroster Powered by electricity and operated by a dashboard switch, the rear defroster button works by initiating energy in a grid of thin wires visible on the inside of the glass, heating the rear window to defog and melt frost, snow, and ice. Most rear defrosters run on a timer that automatically shuts them off after about 10 minutes. The rear defroster starts working immediately, but the front defroster requires more time to get going during cold weather. This is because the front defroster relies on the engine's warm coolant circulating through the heater core before it can blow warm air onto the windshield.

Getting the Most Out of the Defroster Button

Give the defroster adequate time to work properly. Most of us have all been in a rush or running late while trying to get out the door, but it’s important to allow the defroster to sit and do its thing. Every car is different, but giving the defroster at least 5-20 minutes (depending on the weather, how cold it is, and how much snow and ice is on your window) to run will ensure that your windshield is clear enough to drive.

Park facing the east. Park your car so the morning sun hits the windshield. The sun's warmth can help melt ice or frost, working in tandem with the car's defrost function.

Regularly clean your windshield. When your window is layered with dirt and grime, it’s harder for the defroster to work. By keeping your windshields clean often, you’re allowing the defroster’s performance to be up to par.

Don’t clutter air vents with accessories. Obstructing the air vents with objects like air fresheners or accessories restricts airflow and diminishes defrosting efficiency. Maintaining clear, unobstructed vents is crucial for optimal system performance.

Always check to make sure the defroster is blowing hot air. If you have the heat turned all the way up but find that your defroster is not blowing hot air, there could be an issue with the system. Some common reasons for the defroster to be down are: lack of antifreeze; clogged vents; frayed wires; a blown fuse; malfunction buttons or knobs, or cracks in the window tint. Follow up with a professional to properly diagnose and fix the issue.