The test procedure is intended for use in testing and evaluating the approximate power consumption of heavy truck and bus engine cooling fans. The procedure also provides a general description of the equipment necessary to measure fan power consumption, so that the parasitic power consumption of a complete vehicle may be predicted.

The test conditions in the procedure may not adequately match those of the vehicle for which fuel consumption information is desired. In that case, engineering estimates or extrapolations may be necessary. The procedure neglects the pressure drop caused by the radiator core (unless the actual vehicle is used as a test fixture). The effect of ram air due to vehicle motion is also neglected. Those two effects tend to offset each other. Finally, the effect of a fan clutch in reducing fan use and power consumption is not a part of this procedure.