49 CFR § 393.79 - Windshield defrosting and defogging systems.
---
identifier: "/us/cfr/t49/s393.79"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 393.79 - Windshield defrosting and defogging systems."
title_number: 49
title_name: "Transportation"
section_number: "393.79"
section_name: "Windshield defrosting and defogging systems."
chapter_name: "FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "B"
subchapter_name: "FEDERAL MOTOR CARRIER SAFETY REGULATIONS"
part_number: "393"
part_name: "PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 31136, 31151, 31502; sec. 1041(b), Pub. L. 102-240, 105 Stat. 1914, 1993; secs. 5301 and 5524, Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; and 49 CFR 1.87."
regulatory_source: "33 FR 19735, Dec. 25, 1968, unless otherwise noted."
cfr_part: "393"
---
# 393.79 Windshield defrosting and defogging systems.
(a) *Vehicles manufactured on or after December 25, 1968.* Each bus, truck, and truck-tractor manufactured on or after December 25, 1968, must have a windshield defrosting and defogging system that meets the requirements of FMVSS No. 103 in effect on the date of manufacture.
(b) *Vehicles manufactured before December 25, 1968.* Each bus, truck, and truck-tractor shall be equipped with a means for preventing the accumulation of ice, snow, frost, or condensation that could obstruct the driver's view through the windshield while the vehicle is being driven.
[70 FR 48054, Aug. 15, 2005]