CK, it sounds like your compressor is working just fine and your refrigeration guy has charged it properly although that drier does not look like it is strapped to anything.
The problem narrows down to the thermostat's capillary tube not sensing the temperature properly and as Eric mentioned, it may be because you now have a different style with lot shorter probe than the old one, and was made to go inside the cooling compartment.
Did you order the t/s for a slider?
If it was reccomended for your machine, did you coil the new cap tube before sliding it in place? Also I have had sliders where the pipe that the cap tube slides into, has broken loose and not even made contact with the inner linner.
Start by dipping the sensor into a cup of ice to see if it will shut off. If so, then back up the tube again and if still no luck there......lead either the cap tube or the whole t/s directly into the box and make a direct contact with the wall.
Let us know how it works out