Jenn Air JDF2589KES freezer compartment not cooling below 23 deg

[JerryP]

I have a Jenn Air JDF2589KES French door refrigerator that started acting up a few days ago. The freezer section slowly started warming up from 0 to the mid 20s. Since then I have been testing things which means temps go up and the fridge has been slowly being the temps back down but only gets to about 23 on the freezer side and 37 on the refrigerator taking quite a few hours to do that. 
 

Pulled the back panel in the freezer section, there was some ice along the lowest part of the evaporator but not anywhere else.  Evaporator fan worked fine, heater element had continuity and the heating element thermostat gave continuity after being in another freezer for a while and lost it when warmed up. I did not test the thermistor as I wasn’t to eager to cut it off to test.  After running for a day, did get some significant frost build up on the top of the evaporator. 
 

Checked compressor coils, lots of dust, etc., so cleaned them. Compressor fan runs. Tested compressor relay it showed fine but replaced it and the capacitor anyway. Compressor runs very warm to hot (120-130 deg, at 120 I can keep my hand on it but where it is 130, it is too hot for that). I don’t know how long a compressor normally runs before shutting off or how long it would be off for, so I don’t know if it is all the time, but it is on when I check it.  Did check the compressor for resistance and found C-S of 6-9ohms, C-R around 4 and S-R around 10. 
 

Looking at the diagnostic flow chart it seems to point to a sealed system problem, but… I didn’t know if it mattered that it was cooling but not enough, and I ran across a few things that seemed to suggest it could also be a problem with the thermistor or control board, but they didn’t really give much guidance as to how to test. So at a bit of a loss as how to proceed. 

[Trossbarco]

It sounds like a restriction. Pressure readings is the most sure fire way to identify a sealed system problem. You need particular tools and gauges for this. I would not reccomend someone who does not do refrigeration regularly try to tap their system. You can get a thermistor reading at the control board. That is the best place to do it. I reccomend dropping the thermistor in ice water so you know the temp is roughly 32 degrees.

[JerryP]

I should be able to test the thermistor then. Just follow the lines from the freezer to the control board, disconnect the harness and test from there.  That seems like the last thing before it being deemed a sealed system problem.  I believe I have tested everything else that would apply. Anything else I may have missed?
 

I have never played with a sealed system, don’t have the equipment and know the limits of my skills. That being said, I have always heard the rule of thumb that if the compressor is shot, get a new fridge. From looking around for this issue it seems like if it is a sealed system, it is also time to replace. Is that correct, or is a restriction something minor/inexpensive enough to hire someone to do it?

Also, how much should a compressor be running?  I have never really been in a position where I needed to observe one for long so don’t know what I would be looking for to determine normal versus running all the time.