The testing techniques outlined in this SAE Recommended Practice were developed as part of an overall program for testing and evaluating fuel consumption of heavy duty trucks and buses. The technique outlined in this document provides a general description of the type of equipment and facility which is necessary to determine the power consumption of these engine-driven components. It is recommended that the specific operating conditions suggested throughout the test be carefully reviewed on the basis of actual data obtained on the specific vehicle operation. If specific vehicle application is not known@ see SAE J1343. Purpose - The purpose of this document is to provide a recommended test procedure for establishing the power consumption of an air brake compressor or an air conditioning compressor. It is intended that this test procedure be used to determine compressor power consumption over a range of operating conditions@ including both the loaded and unloaded modes. The resulting data is intended for use in the measure of probable vehicle fuel consumption under operating conditions.