The ONLY correct test for your problem is this.
1. Make sure the rear behind the refer(cooling unit area) from the bottom to the top vent is open and clean.
2. IF the refer is in a slide room you HAVE to have a fan at the top outside wall vent blowing out for optimum cooling efficiency.
3. Once the above is correct, you connect the 120 element direct to 120 power with an extension cord and run 24 hours.
4. After 24 hours, the freezer should be BELOW 10 degrees and the Refer should be below 38 degrees.
5. If NOT and the door seals are tight, your Cooling unit is partially blocked and needs replaced.
6. TEST the lower refer with the temp of a cup of water. Doug