Should You Use Cold or Hot Air to Defog the Windshield in Winter?

[JackDella]

Start the air conditioning, set the temperature to the heating mode, and switch the air conditioning to the defogging mode. Use the hot air produced by the heating system to dry the fog inside the car. Introduction to Air Conditioning Defogging: If your car has automatic air conditioning, defogging is very easy. Simply turn on the automatic air conditioning and set the mode switch to the defogging mode. For manual air conditioning, first adjust the airflow direction switch to the defogging mode. Remember one crucial point: when defogging, always switch the air conditioning to the external circulation mode to allow fresh outside air to enter the cabin. Setting the compressor and fan speed to the highest level can speed up the defogging process. If the side windows are not defogging quickly enough, it's best to close the two central air vents to direct the airflow from the side vents more effectively, which can help disperse the fog faster. You can also slightly open the windows to accelerate defogging. Using Specialized Defogging Products: In addition to using hot air for defogging, you can also use specialized defogging products. For example, certain defogging sprays can be evenly applied to the windows before use, forming a protective film on the glass that prevents fog from forming.

[LaJeffrey]

Last week when I was driving my kids to school, I encountered this situation - the windshield was completely fogged up. Turning on the AC is the fastest solution; the air conditioning compressor can dry out the moisture, making the road visible again in just half a minute. But blowing cold air in the middle of winter is really shiver-inducing, especially on long drives which becomes quite miserable. I've now figured out a method: first turn on the AC to quickly defog, then switch to warm air as soon as visibility clears, while also turning on the external circulation to prevent new condensation. Oh, and don't forget to press the windshield defogger button - that small fan-shaped symbol button concentrates airflow on the glass. In winter, it's best to warm up the car in advance; once the engine warms up, the heater works more effectively and saves fuel.

[LeonardoAnn]

Having personally tested it no less than ten times, turning on the hot air when fogging up actually makes the glass even blurrier! Because the hot air bakes the moisture onto the glass, making it denser. Understanding the principle of air conditioning makes it clear: fog is essentially water droplets, which require dry cold air to absorb the moisture. Every time, I directly turn it to the coldest + maximum airflow + internal circulation, and the compressor indicator light must come on for the dehumidification mode to take effect. If you're afraid of the cold, just wear gloves—safety is more important than warmth. After the fog clears, slowly adjust back to hot air, but remember to leave a window crack to balance the temperature difference. Also, don't forget to press the electric heating wire button for the rear windshield—that thing is super effective for defrosting.

[MaryLee]

Last month during a self-drive trip, I encountered freezing rain, and the windshield fogged up so badly that I couldn't even see the road signs. I tried using hot air for five minutes, but it only made the fog worse. In the end, I had to resort to cold air as an emergency solution. A car mechanic shared a secret with me: turn on the AC button (compressor), set the temperature to the lowest, and direct the maximum airflow straight at the windshield. Although it was freezing cold, the defogging efficiency was three times that of hot air. Now, I start the car remotely five minutes in advance to warm up the engine, so the warm air defogs faster when I get in. Wiping the inside of the windshield dry when parking can also prevent fogging, and avoid leaving wet umbrellas or snow boots in the car.

[VanArthur]

Last week at minus ten degrees, I tried three methods: using only hot air for defogging took seven and a half minutes, cold air took just 30 seconds, but the mixed method was the most comfortable. Now my operating mantra is 'cold attack, heat defend': start with a strong blast of cold air to attack the fog, and switch to 27°C warm air plus external circulation as soon as the dashboard is visible. Remember to aim all vents at the glass and close the footwell vents to avoid temperature differences. If there are passengers in the back seat, fogging happens faster, so keep a dry towel handy to wipe the side windows. After installing a heated steering wheel, I finally dare to use cold air boldly, at least my hands don't freeze.