Hi Clive
Yes its a great idia. I installed a couple of computer fans on the upper inside grill for the fridge. These are approx 2" square and I attached them using number plate impact pads. They are very quiet and they suck out the rising heat from the back of the fridge. Last year in France they really proved there worth and we had to turn the fridge down as everything was begining to freeze. I bought a thermostat control kit from Maplins which is adjustable between 18o and 30o. I have mine set to 25o approx,so any warmer it kicks in. I don't know if its better to draw the air out or force the air in as you can wire the fans in either direction, but my logic was heat rises,so assist the circulation by drawing it out.
Any way it works and it does not cost a lot to install. Two fans unless you can get them from a scrap computer as I did with roller bearings on the fan will cost you about