Johnson Control Question (A419)

[larrytate]

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?

[shizzy]

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

[larrytate]

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?

[treetsux]

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.