Unplug the refrigerator power cord from the wall socket to eliminate shock hazard. If the wall socket is tucked behind the refrigerator, turn the relevant breaker switch on the electrical panel to the "Off" position. Secure the switch to the panel with a strip of masking tape to prevent someone else from restoring power while you're working.
Clear the freezer compartment of food items before starting work. Remove all freezer shelves and place the perishables in an ice chest to prevent them from defrosting over the next hour or two.
Remove all screws securing any molded plastic ducts to the back of the freezer compartment with a Phillips screwdriver. Remove all relevant duct work and moldings. If the freezer is fitted with a recessed light, unscrew the cover.
Undo the four corner screws holding the back panel to the freezer compartment and lift the back panel out to reveal the evaporator fan motor.
Make a note of the fan blade orientation and position on the shaft. Pull the fan spindle off the shaft and lay it on one side. Slacken the two bolts holding the fan motor clamp to the back with a socket wrench. Slip the green ground wire terminal from under the bolt head and push it out of the way. Remove the two bolts and pull the clamp off of the fan motor shaft.
Unplug the defective fan motor's wiring harness by squeezing the side clips on the connector and pulling the male plug out of the female socket; remove the old motor.
Plug the replacement evaporator motor wiring harness firmly into the socket until the clips snap into place. Position the two lugs on the back of the motor inside their matching holes on the back of the freezer compartment. Slide the fan motor clamp onto the motor shaft and reattach the clamp to the back with the two bolts removed earlier; slip the ground wire terminal under the left bolt head before tightening the bolts with the socket wrench.
Push the new evaporator fan spindle onto the motor shaft without forcing it back against the motor body. Spin the fan with your finger to ensure that it runs freely.
Replace the freezer back panel and secure it with the four screws removed earlier. Replace any plastic duct work and fittings, and secure all attaching screws.
Restore power the refrigerator and ensure that the evaporator fan turns on. Replace the freezer shelves and close the freezer and refrigerator doors. Allow enough time for the freezer compartment to cool down before replacing the perishable food items.