The set screw is usually recessed inside the 'stat on the front side (where the dial shaft is). In the photo below the set screw is in the 5 o'clock position relative to the dial shaft and brass colored. It was hard to get a good photo. It took several turns clockwise to get it up to 40F and was...
Why use an external controller? You can use a small screwdriver to adjust the set screw on the chest freezer built-in electromechanical thermostat to move it up to keezer temps. It may take a few trys to get it just right, but its free and works. Do this while the freezer is unplugged because...