There are 2 thermistors for frost and 2 for temperature....Fridge and freezer compartment have one each.
Access to the thermistor sensors are from the inside of the fridge and freezer. You have to remove the shelves, trays and the inside panels to get at them.
The manual will show you how.
There are diagnostics you can run that will tell you which one is in trouble.
There are sensitive voltages that may be required to measure. So from a tech point of view you may need someone with electronics expertise to do the measurements.
The procedures and various measurements are too lengthy to tell you but I will give you the link to the service manual PDF and you or someone can do the diagnostics...The Manual is 87 pages long. Can you imagine a fridge needing that much documentation.
That said. I have the same fridge and have fought 3 different problems...not fun....
here's the link...
http://www.ajmadison.com/ajmadison/itemdocs/DA68-01778A-EN.pdfMake sure you unplug the fridge before you go taking things apart...
Good luck
Maytag owns Samsung