S.C. Code Regs. 38-393.79. Defrosting device

Every truck, and truck tractor having a windshield, when operating under conditions such that ice, snow, or frost would be likely to collect on the outside of the windshield or condensation on the inside of the windshield, shall be equipped with a device or other means, not manually operated, for preventing or removing such obstructions to the driver's view: Provided, however, That 38-393 shall not apply in driveaway towaway operations when the driven vehicle is a part of the shipment being delivered.