I struggled with mine for awhile when I first fired it up. Three real issues. One, I had no circulation (fan), two, I kept opening it too much, and three, I was monitoring the temp in the middle with the Ranco probe, which meant I was guessing what the very bottom temp was. Ended up freezing a set of kegs at one point, and dealing with an over-abundance of foam. While others may do anyone or all of those things, I found that doing the following has helped immensely:
1. I added a PC fan to the bottom that blows the coldest air from the very bottom upward. It runs continuous, because I wasn't having much luck having a different fan that I tried first turn on only with the Ranco.... just didn't end up running very often.
2. I moved the probe to the bottom. Now I know what the coldest temp is, and that way I can ensure it doesn't freeze. I set the temp to 32 deg F with a +4 degree range before the freezer cycles on.
3. I bought a cheap indoor/outdoor thermometer for $8 at Menards. Mounted the base station on the back inside of the collar up top and the remote sensor on the bottom. Now reads about 41 at the top and 32 at the bottom when I first open it and read quickly.
4. Leave it alone.
Doing all of the above, especially avoiding opening it every five minutes just to look at the goodies inside has resulted in flawless pours ever since.... and the beer is a frosty cold 38 in the glass.... mmmmm.