How do you get the pulley off the swamp cooler motor?

put lots of penetrating oil on it and give it plenty of time to soak in, then make sure there's no set screw and if so loosen it (it might need penetrating oil also) then insert a flat bar or large screwdriver between the motor and pulley and try to gently pry it off (sometimes tapping the pulley and shaft with a few sharp raps will to break loose the rust) If prying doesn't work, a pulley puller (available at pep boys or most hardware stores) should do the trick. If the motors bad and you're taking it to the shop just leave it on as they're experts on doing this.