Wiring help. Building a fermentation box with an ac unit

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barkerw

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I am trying to build a cold fermenting box for making beer. Building a well insulated 4 x 3 x 5 ft box and planning to use an LG portable 8000btu ac/dehumidifier unit inside the box I have laying around. I have a 2 stage temp controller that I typically use with a stand-up freezer to do this but I need more space so I'm going to build this. My thinking is if I could bypass the digital tstat and just have my temp controller turn the unit on and off as needed I could get unit to cool this box down to 35 or 40 degrees. Not sure how to wire this and what it would mean for the dehumidifier part that is integrated. Attached are picsnof the wiring diagram inside the unit, pic of digitall control wiring and the model tag. Please help.
 

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Bobby_M

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Jumping the black wire to the browns would bypass the thermostat because that's what the relay in the diagram does when it calls for cooling. If you find that the unit freezes up (on the coils), you will probably need to have the unit's fan run full time, even on low.
 
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barkerw

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Thanks Bobby! Could you elaborate for me so I make sure to understand. The Stat circuit board has wires coming in to one side and out on the other. You are saying to connect the black wire on the left to the brown wire on the left and likewise on thw rifht side? Or do I just connect black to black and brown to brown to bypass the Stat?

Also, if my temp controller is wired for a plug and I plug the unit in to it...it will shut the entire unit off and will not be able to run the fan on low all the time. Is there a better way for me to do this? I would like the rest of the unit to stay on and evaporate even when the temp controller shuts off the ac. Is there a way to do this?
 

Bobby_M

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It looks like those two wire bundles might be the CNDISP1 and CNDISP2 shown in the diagram. At least the wire counts look right and the wire gauge is a little thing for the compressor circuits and such. I'm talking about shorting the black wire coming in from the plug over to the brown wire that goes to the compressor so that when the power is turned on, it immediately turns the compressor on. Make sure you're looking at the correct wires.

Where it gets a little tricky, and something you need to confirm, is whether you can lock the fan on or not with the built in controls. Plug the unit in, turn the fan on. Unplug it. Plug it back in. Does the fan start? If it doesn't, you'd have to also short the incoming black wire over to either the black or yellow wire going to the fan whether you want high or low speed.

If it turns out that you need the fan to run full time even when you don't need cooling, I'd approach it completely differently. I'd plug the AC unit in to its own outlet that always gets power. Then create a new plug for your temp controller's cooling outlet and wire it in to the AC unit. You'd just need the hot/black wire and run that to the compressor's brown wire. Now the temp controller ONLY forces the compressor on. The one pitfall here is that you could possibly have the fan turned off and run the compressor by mistake. That would probably ice up the evap coil and possibly overheat the compressor.

There are probably 10 different ways to approach this.
 
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