The cooling coils in the refer compartment frost up after 1-3 weeks which blocks cold air flow to the upper portion of the refer compartment. After manual defrost works fine for 1-2 weeks and freezer seems fine.
GE side by side refrigerator freezer M# PSH25SGSC SV, S# DL406421
Checked defrost heater, thermostat, and thermistor that connect at pins 1-4 with Com on #5 of plug J1 with Ohm meter and all seem fine. There is a 5th thermistor behind cooling coils in refer but I only found the 4 connections on pins 1-4.
Board was replaced ~2yrs ago with part WR49x10152
per box but label on board said WR49x10147. At the time supplier said part is box was correct and latest part regardless on P/N on board itself and it worked fine nearly 2 years.
I would guess it is the board if it weren't for the 5th thermistor which I can't test. Door gaskets good so no apparent air leaks and it really works fine except for the upper part of the refer not being cold after the refer coils frost up and block the rear air duct / cooling tower are flow. The freezer compartment coils were a little frosted when I did the testing but not too bad and only on the bottom 3-4 rows of coils.
Do you know where that 5th thermistor connects so I can test it?
Got any ideas what is wrong and how to fix?