Hi, thanks for using JustAnswer.com. May I please have the model number of your refrigerator so I can give you specific instructions?
Okay, here we go. You will need to remove the drawer and the shelf. Next, remove the icemaker if it has one. There will be some 1/4" screws holding it to the side wall. Next, there are a few 1/4" screws in the rear panel, remove them. There is likely a white plastic air diverter at the top center of the back panel that has little clips that will need to be released to remove the back panel. You will also need to pinch the tabs for the icemaker harness and push it behind the panel. Also, thee is likely a small white housing on the upper RH corner that holds the thermistor. Use a screwdriver and release it and push it behind the panel as you pull the panel forward. Once the panel is removed, you will hav access to the evap fan. I am sure it will be the white plastic one marked "Made in Sung Shin"...replace that fan motor.
Sorry, I gave you instructions for a bottom mount...my oops! Remove the icemaker, if there is one. Remove the back panel by removing the 1/4" screws and pull the panel out. You will see thefan once the rear panle is removed...