if you have the new thermostat, id just turn off the fridge at the power (obviously) pull it out and look down the bottom, there will be a small round black thing hopefully just like the one youve got (like a half inch coin roll size) just look where the wires go and swap it, It should be near the big compressor so it knows when that gets hot, thats the thing that looks like a gas bottle, if you got the right one it should be too easy.
sometimes there might be a plastic casing around all of that just carefully use a screwdriver to pop stuff off.
Good luck
steve the fiddler, October 2008