This fan is available as a popular option for camper refrigerators. While yours may or may not be a factory install (you stated you bought it used), many folks install these fans to help the coils "breathe" better. the heat generated on the back of the unit is ducted to the ceiling and out the roof vent, but cooling efficiency can be greatly improved by the addition of the fans. They are generally wired to 12v, and have a built in thermostat that makes them come on above 80 degrees, I think. Some factory ones are rather noisy, but aftermarket fans are available that are very quiet, and draw a very small amount of power from the battery. Once cooled below their set temp, they will shut off. Hope this helps you, as the fan is there to make your fridge work better.
/SIGPIC]'08 V-lite Flagstaff 30WRLS
'06 Ram 1500 QC hemi
Reese dual cam sway control,
K&N series 77 intake, Hellwig helper spgs. LT tires,
Flowmaster "true duals", 380 h.p., Bilstein shocks