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Johnson Control Question (A419)

Hi guys,

I have a new Johnson Control unit for a chest freezer fermentation chamber. The unit is not behaving properly. When set at 65 degrees, three different thermometers inside my chest freezer read 72 degrees. Ordinarily, I would just set my temperature 7 degrees colder than my desired temp to compensate, but the relationship between the actual temperature and the set temperature is not linear. As a result, I am unable to keep a satisfactory temperature setting. I think the probe may
be malfunctioning or defective.

Should I just try buying a new probe and wiring it up? Something else I can try?

what kind of thermometers and where are they placed? and where are you placing the temp controller probe?

Two different Thermapens and an analog thermometer all give me the same temp. I placed them all inside a coffee can on the compressor hump. There is definitely something wrong with the Johnson controller: it is the only one that gives me a high reading.

I guess there is no way to tweak/adjust the controller?

I dont know if this helps you but I use a small bungee and bungee the probe between the keg and some bubble wrap so its not taking the reading from the air, but rather something that wont fluctuate as much.

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