Johnson Controller broken... now what?

[AmandaK]

Hey guys, I had been using an older model Johnson Controller for my keezer. I think I kinked the copper temp probe on accident and now my freezer will not turn on.

My problem is mainly that I have friends coming over in 24 hours to drink my beer.

What is the quickest and dirtiest way to get a temp controller for this thing? I've contemplated buying a mechanical home thermostat and ghetto rigging it to the relay in the freezer. Anyone else done that?

Or have any other suggestions?
Thanks!
Amanda

 

[MalFet]

Yep, that should work. It will be a pretty rough and tumble approximation of temperature, but so long as the home thermostat goes down to the temperatures you are wanting it will work fine. Analog home thermostats are typically relatively simple bimetal switches.

 

[AmandaK]

Perfect. That's what I was thinking.

Now, how would I wire this thing? I think the relay only has a positive wire in. Would I just take that out and replace it with the positive wire from the mechanical thermostat? And is it really necessary to ground the thermostat if it is the mechanical kind?

 

[MalFet]

Perfect. That's what I was thinking.

Now, how would I wire this thing? I think the relay only has a positive wire in. Would I just take that out and replace it with the positive wire from the mechanical thermostat? And is it really necessary to ground the thermostat if it is the mechanical kind?

The thermostat doesn't need a ground because it is only a switch. It is not actually a relay itself. Think of it a little elf that sits there all day and connects the wires and pulls them apart again based on temperature.

I don't want to make too many assumptions about your freezer because I don't want to electrocute you, but typically a simple two wire thermostat would sit on a single wire leading to a relay, as you describe. What kind of device is sitting there now? Some kind of dial?

 

[samc]

http://www.wortomatic.com/articles/Remote-Sensing-DIY-Controller-for-Less-Than-$25

 

[AmandaK]

Okay, I finally got home from work to look at this thing. It's a newer GE freezer. It has a dial on the side. I have it sitting at the highest temp it can hit to see what that is. And as it turns out, this little project might be much easier than I'm making it out to be. There's a wire coming from a temp. sensor in the freezer heading straight to the relay. Looks like I'll be breaking into that.

Thanks for the link, samc! If my upper temp range of my current dial is too cold, I'll head out and get me one of those!