The large Waeco compressors fridges suck up huge amounts of power. If you want to hear a sad tale of trying to run one of these in a hot climate read as much of this as you can stand: http://www.exploroz.com/Members/145028.75/1/2009/Queensland_Adventures_Winter_2008.aspx?p=%2FBlogs%2FDefault.aspx
I had one of these beasts and on warm days it could easily drain 100 AHs or more. Having adequate external ventilation is a big factor. Make sure you have large openings under and above the unit for ventilation. Next check your wiring. These larger units pull about 7 amps. Depending on the distance from the battery bank, you may need an upgrade. I went to 6 gauge wiring. I finally gave up trying to feed the beast and replaced it with a small NovaKool. I cannot answer the question about an internal fan. I did try one of the battery operated refrigerator fans with the NovaKool but found it to be of no use. The smaller unit seems to maintain fairly even temperature without a fan.
