Temp control not controlling temp

I'm using a GE 5.0 cu/ft freezer unit with a Johnson's Controls temp controller. I have the temp control wire taped on the inside towards the middle of the freezer. Is this right?

Have temp set at 38 but holds more towards 43-44 degrees. What gives?

Need more data. "...taped on the inside..." of what? Are you trying to control ambient temperature or liquid temperature? How are you measuring the 43-44 degrees?

What is the differential set to on the temp controller?

I have the wire with the thermometer at the end of it, taped to the inside wall of the freezer.

I have another thermometer inside the freezer measuring air temp. My desire is to have 38 degree liquid or beer.

I have it set to 38. When I notice it isn't cold enough I turn it down to 36 and the air temp is in the low 30's. I worry about freezing my brew so I turn it back to 38 and I get 44 degrees.

A few things to test:

First, placement is important and right now you are comparing two different things. A lot of freezer units have their coils in the wall, and if you've got your themometer smack up against them you're going to get a colder reading. Hang your temp probe in the air just like the thermometer and see if that fixes it.

If it doesn't, calibrate your air thermometer. Stick it in a cup of slush ice water and make sure it reads 32F, and then again in a pot of boiling water (if it can handle that range) to see 212F.

Better yet, attach the temp controller's temp probe to the fermentor. Insulate it with bubble wrap or something like that and you can then just control the beer's temp instead of the ambient.

DogFlynnHead said:

I have it set to 38. When I notice it isn't cold enough I turn it down to 36 and the air temp is in the low 30's. I worry about freezing my brew so I turn it back to 38 and I get 44 degrees.

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The air temperature will swing around much more than the liquid temperature will. That's fine. The method I suggested will make sure the two are equivalent, but you can also (as another poster mentioned) tape it to a keg and attach some insulation on top.

FWIW, I see more than 7* difference between lid and bottom in my keezer.