Freezer Thermostat doesn't seem accurate

Hi Folks,

I recently bought a 7cu. ft. Holiday chest freezer and a Johnson Controls A19AAT-2C Freezer Temperature Controller to manage the temperature. I just ran the probe under the freezer lid through the back and laid it on the hump with a dry washrag under it to keep it from touching the metal bottom directly. I also have a regular dial thermometer inside there next to the probe so I can see the enironment temperature. I set the thermostat dial to about 35 degrees, and my freezer is on the coldest setting, but the thermometer inside the freezer reads at about 48 degrees. The damn thing seems about 10 degrees off but this is a simple thermostat, and no calibration can be done. I was just wondering if anyone has a similar setup with similar issues? Please let me know what you think. I will probably post some pictures later.

I don't have anything inside of it, but I plan on sticking a carboy of Ed's Apfelwein in there this weekend and want to see if anyone has any advice on getting the temerature to be more precise. (Aside from the obvious method of figuring what temp I want and setting the dial 10 degrees lower, I would hate to find one day that it decided to use the right temp and I have it 10 degrees under what I was expecting.)

Thanks in advance for the help!

did you feel inside it? does it feel like 48? or colder?

you can check the probe by unwiring it from the unit and check the resistance.

I did feel inside the freezer. It felt pretty cold but I'm not a great judge of that based on just touching. Here are some pics. I know the pic of the thermostat is fuzzy but that may not be that crucial.

These Johnson controls are accurate to withing +/- 3 degrees. We've sold them for years and I've only had three returned - in all three cases the issue was a cracked or kinked tube that runs to the bulb.

You need to put the thermometer in a glass of water then place the glass in the freezer for a better measurement.