Johnson Digital Temp Control Settings

So I've been running my 14.2 cu ft Frigidaire (i got on Craigslist for $125 ) with my Johnson controller i got in last Friday.

Right now, I'm only using the freezer for fermenting/bottling storage. ( my first batch is bottle conditioning right now and just received my ingredients for my second batch).

My question is what the setting mean for the thing. I've tried google and i got nothing. I know what the setpoint (SP) is, and the differential setting (certain degree setting, i used 3 degrees, that tells when the compressor should kick on and kick off if it drops over or below my setpoint temperature, Correct?)

But there are 3 more settings that i do not know what they mean.

There is the anti-short cycle delay. Which from what i've found means the following: For technical aficionados the Johnson does have a feature called Anti-Short Cycle Delay. Cycling is the rapid turning off and on of an electrical device. Over time cycling can harm your appliance. The Johnson controller allows you to set a time interval, in minutes, that keeps the controller from turning on right after it shuts off no matter what the temperature reading is. This can be very useful when you are using a 1 degree of differential setting for tight control but want your compressor or power supply to have a minimum time period of rest before it turns back on. Temperature Range of -20 to 220F.
Which from that, i gather that it helps to save your compressor from crapping out on you if you can't keep your temperature. Tell me if i'm right in this example.
I set the freezer to 68 degrees. Compressor kicks on, cools to 68 then shuts off. Well 5 minutes later my temperature is 73. This feature should stop the compressor from kicking on in only 30 minute intervals if i have it set to this, correct? My freezer doesn't have this temp loss problem. It usually takes 2 or 3 hours to lose enough heat to restart the compressor.

There are 2 other setting i can't remember off the top of my head. What setting do you use? What are the other 2 and their purpose.

The ASD keeps the fridge/freezer from cycling too often. I don t know what the recommended setting it, but I think I have mine set to 5 minutes. I can't imagine setting it any lower than that is going to affect your beer.

There are jumpers inside which set a) whether it's controlling a Cooling device (Temp goes down when controller is in ON state) or a heater (Temp goes UP when controller is in ON state), or b) whether the controller turns ON at the set point, or turns OFF at the setpoint. You have to factor in the DIFFERENTIAL with that as well.

I am re-reading the manual and it looks at though the OFS (Offset) is for the use of a secondary device, that I think would turn on the controller like a timer, or some other machine. I just set mine to 0 since I see no reason to use it yet.


So if you wanted to Chill your fridge to 65, you could set the jumper inside to "CHILL" and have it CUT-IN at a setpoint of say, 66. Set the differential to 3 degrees and it will cut out at 62. You'd have to play with the number to see where the sweet spot it for your setup, but the main point is that your going to be around 65 most of the time.


It usually take me a few minutes of thinking about it to get the settings all straight in my head.

So if you wanted to Chill your fridge to 65, you could set the jumper inside to "CHILL" and have it CUT-IN at a setpoint of say, 66. Set the differential to 3 degrees and it will cut out at 62. You'd have to play with the number to see where the sweet spot it for your setup, but the main point is that your going to be around 65 most of the time.

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Well it's a freezer and i'm in the south, so it will always be on chill. The factory default is set for chill i believe.
So right now i have it set at factory defaults, except my setpoint is at 68 degrees, and my diff is set at 3 degrees. So this means that if it gets over 68, it will cool down to 65 and shut off?

Also, how do you have your sensor arranged. Right now i have a plastic cup with about 3 inches of water and i have the sensor resting in there. Is this sufficient for good reads?

BugAC said:

Also, how do you have your sensor arranged. Right now i have a plastic cup with about 3 inches of water and i have the sensor resting in there. Is this sufficient for good reads?

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You'll get conflicting opinions on this, but I prefer to tape the sensor to side of the fermentor of the most recently brewed batch. It also helps to put a folded up paper towel or rag over the sensor to insulate it from the air in the chamber a little bit. Very active fermentations can raise the beer temp significantly, and I'd rather control the temp of the beer than the ambient surroundings.

I've heard of people placing the sensor in a bit of water, as you have, but if I would probably tape to the fermenter under a bit of foam insulation, like JuanMoore says.

That is until I get my 1-wire network all set up and can actually see the temps in the fermenter and compare to the temp inside the fridge and the ambient air temp. But it's just geek play. Honestly, I don't think it's going to make or break your beer if your temp isn't a steady flat line. Just having a ferm chamber with a temp controller will be good enough.

In fact, I just brewed a Lager last night and my probe is just dangling.