Unplugged refrigerator and removed access panel from back of fridge. Have had this panel off many times for dust removal. Panel is a cheap piece of glorified cardboard on this Whirlpool model, which is a shame given that it was a $1000 refrigerator. Fan motor is mounted on stamped sheet metal bracket which I removed from cabinet with old fan attached to it. Metal bracket held in place by 4 1/4 inch hex head sheet metal screws. Two outermost screws can be removed with nut driver but access to inner screws blocked by plumbing so used small 1/4 inch box wrench to remove them. Once unscrewed, the bracket plus old fan can be angled out of the cabinet. When bracket was out, removed old fan motor and washed 20 years of dust off bracket. Then pushed new fan onto new motor shaft. A firm push is required. Be sure to match configuration of new fan on new motor to that of original fan on motor so your fan won't be blowing backwards. Used large socket wrench over plastic fan shaft to distribute force and avoid breaking plastic fan. Pressed until gap between new fan and motor matched gap of original fan to original motor. Then attached new motor and fan assembly to bracket. Will only go one way for holes for 3 attachment screws to line up. Angled bracket and new motor back into cabinet and attached to mounting point with original 4 screws. Plugged new motor into original electrical plug with adapter plug that came with new motor. Can only go one way so you can't mess this connection up. Plugged refrigerator back in and fan started immediately, blowing in the correct direction with no ugly noises.