Interpretation ID: aiam3366
Branch Manager
Mazda
Toyo Kogyo U.S.A. Representative Office
Detroit Branch
23777 Greenfield Road
Southfield
MI 48075;
Dear Mr. Ogata: Thank you for your July 24, 1980, letter concerning your efforts t improve defogging performance. We share your concern about providing optimum driving visibility and are pleased with your efforts to improve this safety feature.; Your letter requested an interpretation of Federal Motor Vehicle Safet Standard 103, asking whether it is permissible to designate an intermediate blower fan speed (instead of the maximum speed) as the speed to be used when defrosting, if some caution or direction about the necessity for using that intermediate speed for defrosting purposes is provided in the Owner's Manual. The purpose of taking that step would be to cause the intermediate speed instead of the maximum blower speed to be used in testing the performance of the defrosting system under the standard. If this was permissible, you could increase the speed of the fan at the maximum position, thereby improving performance of the defogging function, while still being able to meet the performance requirements of the defrosting function at the intermediate speed (but not at the new maximum speed).; Paragraph S4.3 of the standard states that ' t he passenger ca windshield defrosting and defogging system shall be tested in accordance with the portions of paragraphs 4.1 through 4.4.7 of SAE Recommended Practice J902, August 1964, or SAE Recommended Practice J902a, March 1967, applicable to that system,' with certain exceptions not applicable to your question.; Section 4.2(g) of SAE Recommended Practice J902 specifies as one of th testing conditions that the defroster system air be 'On full, Blower on high.' Similarly, section 4.2(g) of SAE Recommended Practice J902a specifies that the defroster system air be 'On full. Blower on high speed.' We therefore conclude that it would not be permissible under the standard as currently drafted to install a defrosting system which fails to meet the standard when the blower is set to its highest speed even if the system meets the standard at a lower blower speed and that lower blower speed is labeled as the maximum defrosting position. This conclusion would not be changed by the inclusion of directions in the Owner's Manual or words or symbols on the control panel.; If you are unable to resolve the problem in another way, i.e. improving the performance of the heating element, you may wish to petition the National Highway Traffic Safety Administration for an amendment to FMVSS 103. It is our inclination, however, that a defrosting system which operated optimally at a lower blower speed would cause considerable consumer confusion. Drivers would normally expect to obtain both optimum defrosting performance and optimum defogging performance at the highest blower speed. Even if the system was clearly labeled to indicate that the blower speed should be set to medium for defrosting and high for defogging, many consumers do not know the difference between defrosting and defogging. We would also have to consider the amendment's effect on Standard 101, since there is only one symbol for the defrosting and defogging system. If you should decide to petition for an amendment to Standard 103, we would like to see these issues addressed.; Sincerely, Frank Berndt, Chief Counsel