"This standard applies to all types and sizes of air-conditioning units@ heat pumps@ and chillers using direct-driven 250 mm to 750 mm (10 in. to 30 in.) diameter propeller fans@ which@ for the purposes of this standard@ are called a ""system."" This standard covers system vibration problems excited by unbalance of the rotating parts@ aerodynamic forces acting on the fan blades@ and electromagnetic forces in the motor. This standard does not cover system vibration problems excited by the compressor in the unit or by external sources such as the structure supporting the system. PURPOSE This standard establishes laboratory and on-site diagnostic test methods for identifying causes of vibration problems involving direct-driven propeller fans for condenser cooling in air-conditioning units@ heat pumps@ and chillers."