blower motor works when it wants to

my blower motor only works when it wants to. have checked fuse and relay, they're ok. it'll work for a week then quit. any help would be appreciated!!!!

Take blower motor out from under the glove comp. via 3 screws. unplug and smother every open spot with 3 in 1 household oil. then plug in and turn on. watch your self b/c oil with be slung out. you may also have to give it alittle push start. once it starts turning by itself. turn off and oil again. the place back into the space under your glove comp.