
Proper windshield defrosting is critical for winter safety because Federal Motor Vehicle Safety Standard No. 103 mandates that defrosters act as primary active safety equipment to preserve driver visibility. Federal regulations require modern defrosters to clear at least 90% of the driver's primary viewing zone on the windshield within 8 minutes at −18°C. When a vehicle's heating and defrost system fails to clear frost, ice, or interior condensation rapidly, severe visual impairment drastically increases collision risks during icy lake-effect weather.





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