What Causes Frost Inside a Car?
2 Answers
Frost inside the car is caused by water vapor produced from human respiration. During winter, when the outdoor temperature is low, parking the car outside for a while can lead to frost forming on the interior glass. If there is frost on the inner side of the windshield, it is recommended to use a towel soaked in warm water to wipe it off. When parking outdoors in winter, covering the front windshield with a cloth or blanket at night can effectively prevent frost formation. Solutions for Frost Inside the Car: Warm up the car thoroughly to allow the engine coolant temperature to rise. If there is frost on the front windshield, avoid using the wipers to scrape it off. Instead, let the car idle to warm up and patiently wait for the engine coolant temperature to rise. During this period, do not turn on the heater. Use warm air to blow on the front windshield. Once the engine coolant temperature has risen, turn on the heater and set it to blow upward onto the windshield at the highest setting. This usually takes 5-10 minutes. Promptly wipe off the frost with a cleaning cloth. When the warm air has melted the frost on the outside of the glass, gently wipe the frost with a car cleaning cloth to speed up the melting process. The melted area will gradually expand. When wiping, press lightly on the frost to ensure it has melted before wiping. If the frost is too thick, use a snow scraper in combination. If there is both frost and snow on the car's exterior windshield or other areas, in addition to the above methods, using a snow scraper will yield better results.
Last winter, the car windows frosted up just five minutes after driving out of the underground garage—it was like a freezer. The main culprit was the huge temperature difference between the inside and outside of the car: sub-zero outside versus over 10°C inside, causing moisture to freeze directly into frost on the glass. There were also a few hidden accomplices: lingering moisture in the seats and carpets after eating hotpot in the car, aging seals letting in drafts, or even forgetting to close the windows slightly the night before. The worst was getting out of the car with the recirculation mode still on—trapping all the warm, humid air from breathing inside, instantly turning the glass frosty when it met the cold. Now, I always run the external air circulation for five minutes before parking to vent out the humidity and wipe the windows dry before leaving.
