temp controller issue/question

So I just built myself a fermentation chamber and used the aquarium temp controller STC-1000 that many others have used and seen here
https://www.homebrewtalk.com/f51/ebay-aquarium-temp-controller-build-163849/

anyway it seems to be working to a point but I'm not sure if I wired it wrong or just don't understand the operating procedure.

I only have a heat source at this point (light bulb), there is no cold yet and nothing plugged into the cold outlet. It works and heats up the chamber to the specified temp but then the controller switches from heat to cool function and keeps the heat source turned on, heating the chamber past the desired temp.

Any ideas? I just started a batch of cider and need to get this dialed pronto.

thanks

If you used only one duplex receptacle, did you break off the tab between the two hot screws?

hmmm I'm not sure where the tab is so that is probably my issue, only used one duplex. where is the tab exactly?

the other part of the problem is that F2 function was set at the default .5 deg c. The light would shut off at the target temp but the temp inside the ferm box would rise past .5, once it went past the .5 it would switch to cool function and turn the light back on.

On the side of the receptacle, in between the two brass screws, there is a small piece of metal that connects the plates that the two screws are screwed into. This tab needs to be broken off with pliers in order to isolate the two receptacles. Bend it back and forth a few times and it will break off. These two screws should be where the cooling hot and heating hot connections are made correct?

You will need to determine how much cooling undershoot and heating overshoot occurs in your fermentation setup and set the controller differential above the larger of the two. You can get the undershoot and overshoot to their minimum by attaching the probe, under insulation, to the fermentation carboy or bucket. The thermal mass of the fermenting beer helps mitigate this issue.