Hi all. My kegerator flucturates from 36* to 41* over the coarse of 40min. Seems like all of these cheap mini fridge units are like this. Is there a fix to get this to be more stable? Maybe an external temp control or an internal adjustment?
You could add an external thermostat and set the Differential setting to a low value, like one or two degrees. That would reduce the range of temps you're seeing. But it would also cause an increase in on/off cycling, which will shorten the life of your compressor.
If "stability" is your only concern, keep in mind that what really matters here (from the beer's temperature standpoint) is the average kegerator temp. Beer has a lot of thermal mass, and really isn't bothered at all by a swing of (in your case) 5 degrees back and forth in ambient temp.
I wouldn't worry about it, honestly. Your beer is cold and 5°F fluctuation won't affect it. I don't think you'd accomplish much with an external temp controller. I'd just let it be and enjoy your beer.
I would invest in longer draft lines, inline pressure regulators, and adjustable flow taps before I worried about the temp fluctuation.
Prior to having a dedicated fridge for fermenting, I would use my kegerator dual purpose. When fermenting in the kegerator use an external temperature controller. When serving from the kegerator, the internal thermostat works fine.