Thought I'd mention a technique I read about. Haven't taken the time to do this myself but I mentioned this to one of the members who later told me they tried it and it worked pretty good. If that member sees this, perhaps they will respond. The idea is to normalize the big compartment temp swings and frequent compressor starts/stops due to changes in air temp just from opening the door. Taping the temp to the vessel is one idea but could be a pain depending on controller. Another idea is to place the probe in an independent vessel of water that just stays in the cooler. Obviously, the liquids change temps less quickly (and why a full cooler stays more stable than an empty one - just in case you needed another reason to keep your cooler full of beer).

Anyway, the simple way around this is to take an old White Laps yeast vial, drill a hole in the top large enough to insert the probe (may cut a slit to slide the probe wire in sideways if the end is too large), add water and seal it back up. The vial full of water will regulate the temp and will not be as prone to large temp swings in the cabinet just from opening the door.

Might be some difference between the internal temp in an active fermenter (from the fermentation process) and the vial but you could estimate this with a separate thermometer against the fermenter just once and adjust your controler temp accordingly when fermentation is ongoing if you use your cooler for both fermentation and conditioning.

Sounds like a good idea the second time around. Maybe I'll try this..... maybe I'll have a beer first and think about it some more.