If you are mechanically and electrically handy, yes you can, depending on the AC you have.
My AC fan started making a lot of noise and stopped turning. Pulled the motor out and found the bronze bushings were riveted in. I carefully remove the armature from each half of the motor housing and found they weren't worn out just dry of grease. I drilled the rivets out, polished the shafts, heat greased the bushings, and reassembled with screws.
Still running well after maybe a year and a half.
If the bushings are worn you may not be able to find replacements.
You can always replace the fan motor. Most are sold on ebay.
Probably more than I can handle. Lol. I'll climb up there to check brand and model. It's pretty old.