Interpretation ID: aiam1965
Assistant Vice President
Engineering
Mercedes-Benz of North America
Inc.
P.O. Box 350
Montvale
NJ 07645;
Dear Mr. Gerth: This is in response to your letter of May 5, 1975, asking at what poin the test voltage may be measured during testing for compliance with the Standard No. 103, *Windshield Defogging and Defrosting Systems*, requirement that the blower motor test voltage be 15% over nominal system rating at the blower motor or the supply end of the motor dropping resistor. Your question relates to the meaning of 'the supply end of the motor dropping resistor.'; Measurement of the blower motor test voltage should occur at the suppl side of the motor where there is no resistor. Where the system contains a resistor, the voltage should be measured at the supply side of the resistor, not between the resistor and the motor. The reason for this is that the test voltage level specified in the standard is intended to relate only to the voltage as it is fed into the defrosting and defogging system. The purpose of the voltage level specification is to assure a system capability to handle voltage levels that will normally be encountered during operation of the defroster and defogger. This can be accomplished by measurement of the voltage before the current reaches the resistor.; Yours truly, Richard B. Dyson, Assistant Chief Counsel