You can run different sounds

Reason and solutions:1.Brush-check the bearing of the stator and rotor,rotor deformation,whether for

repair or replacement 2.- poor lubrication bearing damage or three phase generator replacement bearings,Motor vehicle bearing cleaning 3.Motor open phase running,check and repair the cut-off points 4.Blades touch the chassis-check and eliminate electricalmotor1.blogspot.com the fault