Take blower motor out 3 screws and unplug push gas pedal down and remove assembly take 2 screws ot of the back of assembly and separate black backing from assembly. If you used drik holder on dash most likely you had a spill from time to time. When assembly is opened look into gap armature where 2 brushes make contact is probably black take sandpaper and put into hole at contact point where brushes hit and rotate motor by hand until copper is exposed do not push to hard just enough to remove residue. reasemble in the reverse order you to it out. Plug in to harness and try it out before install to confirm it is working.
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Take blower motor out 3 screws and unplug push gas pedal down and remove assembly take 2 screws ot of the back of assembly and separate black backing from assembly. If you used drik holder on dash most likely you had a spill from time to time. When assembly is opened look into gap armature where 2 brushes make contact is probably black take sandpaper and put into hole at contact point where brushes hit and rotate motor by hand until copper is exposed do not push to hard just enough to remove residue. reasemble in the reverse order you to it out. Plug in to harness and try it out before install to confirm it is working.
Check the blower speed controller, that is most likely the cause.