I have a Johnson Controls A419 digital controller that I believe has s**t the bed.
Two days ago, the GFCI outlet that my two freezers hang off of popped. I reset it and started watching. Four hours later, the GFCI blew again. I stripped the whole circuit load down to the bare minimum (one freezer+controller, one fridge; only one freezer+controller was hanging off the GFCI) and lo and behold, the GFCI blew. I swapped freezers (my lager fermentation freezer is currently idle) and the GFCI blew again. So, clearly the controller is the only unique item here.
Interestingly enough, I reset the GFCI one last time and pulled out my multimeter to figure out what was blown up. The controller flashed “ASd” on the screen for a few solid minutes (~2), and then turned on the freezer – even though the probe temperature was within the set point and the hysteresis band. The GFCI fault is weird enough in and of it self (I haven’t been able to figure it out), but the controller running amok is truly odd. I put another object in the freezer and let it run; it ran the freezer down to a probe temperature 27dF (no GFCI fault this time) even though the set point was 66F with the hysteresis band set to 1dF.
I’ll be calling Northern Brewer tomorrow, but figured I’d throw this out there to see if people have seen this before or if they haven’t… know there may be an odd little failure mode within this controller.