Originally Posted by derekm
I like to put my sensor in a thermowell in a two liter coke bottle filled with water. It should greatly prolong the life of your compressor and stop large temperature fluctuations.
You actually will do better with a sensor taped to the wall of the freezer. That assumes you can set the controller to an appropriate cut in / cut out. If it's one you can't set, it's likely already set up for "tape to the wall".
I know this sound like you are not controlling things as well. Think of it as controlling the temperature before it gets to the keg.