Johnson Controls A419 question

[anico4704]

I thought I knew how my Johnson Temp Controller works, but apparently I don't. I have it set to cooling cutout SP 35 DF 1. I thought it would turn on when it hit 37 and turn off when it hit 35. What it does is turns on at 36 and turns off at 34? I don't know if it gets all the way to 34 but I thought right when it switched from 36 to 35 that it would turn off right away? Thats definitely not what it does as I see it on still when the temp reads 35. So why is it turning on at 36 and not turning off right when it turns 35?

What am I missing here?

 

[CadillacAndy]

I thought I knew how my Johnson Temp Controller works, but apparently I don't. I have it set to cooling cutout SP 35 DF 1. I thought it would turn on when it hit 37 and turn off when it hit 35. What it does is turns on at 36 and turns off at 34? I don't know if it gets all the way to 34 but I thought right when it switched from 36 to 35 that it would turn off right away? Thats definitely not what it does as I see it on still when the temp reads 35. So why is it turning on at 36 and not turning off right when it turns 35? What am I missing here?

It goes 1 degree in either direction. That's exactly how mine works too. I have mine at 51F for lager ferment but it kicks on at 52F and runs until it's 50F and then shuts off and sometimes even drops below 50F because the type of fridge I have. Wish it had tighter control but it works well enough.

 

[AnOldUR]

Actually, the way I read it (and the way mine works), it's not supposed to be in both directions, but only up or down from the setpoint. With my Ranco, if the differential is set to one, it only allows a 1 degree raise in temperature before turning on. My Johnson will allow 2 degrees. When in heating mode, if it's set for 150 degrees with a 1 degree differential and cut-out mode, it will turn off at 150, but instead of going on at 149, it turns on at 148. Not what I would like! In my book that's a 2 degree differential.
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