I would check for proper ventilation. If not installed per refer installation instruction fix it.
Distance between outer wall and coils should be less then an inch. I fixed mine by using foam board attached to outside struct wih Liquid nails.
If in a slide, there is normally a void on top of refer. This needs to have a curved section of sheet metal to divert air into the top refer vent.
Not in a slide is little hard to do, but can be done by removing roof vent.
If you are set on installing a fan, use a 12 volt fan connected to the 12 DC refer supply wires. The small computer 12 volt fans work good.