Freezer Too Cold

Freezer running too cold. Everything else OK. Display says -21 degrees F and a thermometer inside agrees. Control is set for +6 degrees F. Ran diagnostic with control panel and it said both themistors are OK. Should I go ahead and replace the main circuit controller board or is there some other part like a thermistat to test?

I had to replace the drain tube on the freezer section of my refrigerator but I am having trouble determining where the other end connects to keep the water from draining on the floor. Any directions would greatly be appreciated.

The Appliance Parts Pro part number is AP4369159.