Blower motor hums.check capacitor,it's good.check fan relay,it's good.it runs sometimes,sometime it doesn't.

Set the tstat to fan/fan only,, watch it to see if fan motot runs for a while and then stops, if and when it stops feel motor and see if it gets hot,real hot,be careful, if it does,, you probably have bad bearings that are seizing up, if so replace motor and capicitor