Just sort of an FYI message. I had an original Ranco temperature controller controlling my lagering fridge (not the one I keep the yeast library, or the serving beer in). Everything appeared normal from the outside, it turned on periodically, turned off periodically, and sounded normal. This is not a fridge that I check often, things just sit in it and age.
Last night, I was making preparations to brew on Sunday, I was going to use the fridge to be a fermentation fridge instead of a lagering fridge. When I opened it, it was too warm. Turns out the Ranco had somehow reset to some strange settings, and would no longer allow me to change them. Its now permanently stuck on a 35F set point, with a 17 degree differential. That means its dropping the temp to 35F, but allowing it to slowly raise up to 52F before it starts dropping the temp again. When I try and change any settings, it tells me E2 which means memory write error. I've tried everything to revive it, no luck.
So, if you guys have any fridges that you don't check often, I don't recommend putting anything that temp is critial in them. The yeast library for the club resides in my drinking fridge. I check that every day, so if the re is a problem, I will discover it.
This is my first temp controller failure, and its on what I always considered the better of my commercial temp controllers. My homemade ones are all still working strong.