camelracer,
This spring while installing my furnace I had to remove the frig to run the gas line and to access the wiring hidden behind the insulation blanket. There is very little insulation on the sides of the compartment and none on the top. The manufactures spec.s say the frig box should have a max of 1/2" clearance on the sides and top and a min. of zero. I pulled the frig again and insulated around the box top and sides, rebuilt the heat shield/baffle above the works and closed the sides to isolate the frig box from the outside air. So far the performance has improved with the extra insulation.
Regarding clearances, the manufacturer of your fridge wants a chimney effect to develop an efficient "draft" to remove heat from the cooling fins. Too much dead air around the fridge negates this effect, and the fridge is therefore less efficient. This is true of both absorption and compressor type cooling units.
Regarding fans, an interior (inside the fridge) fan keeps temps even throughout the compartment. The fridge should run less often, and food should last longer if one of these are used. A fan to cool the outside (rear) of the fridge should be placed in such a way to support the chimney effect mentioned above. IMO, the outside fan makes a HUGE difference in the efficiency of the fridge, and is worth every effort to install, when installed properly.
DLN, I am not surprised at all that your fridge works better with the insulation you added. It should go without saying, but I'll say it anyways, if anyone is inclined to re-work the install of your fridge to tighten up clearances, be sure to use appropriately rated fire-resistant materials. The back of the fridge can get HOT! Over the years of camping in and working on RVs (professionally) I have not often seen the fridges actually installed to the specific manufacturer's recommended clearances, etc. There are too many variables, too little attention spent on this detail. That is to say, everyone should check the install of their fridge, if they want the most out of it.
Regards,
Bob