Good morning all. Several days ago, my I noticed ice in the middle vents of the evaporator cover. Ran diagnostic, got r1d fresh food fan error, pull out shelves and cover frozen in place. Left doors open and intermittent hair dryer, after a couple of hours fan begins running so I re-run diagnostic and no errors show. Pull cover, defrost evaporator and fan completely then reassembled. Now fan wont run, diagnostic shows double 88 with no errors. Check main board, getting 8.2vdc out to fan, and 2.2vdc return, within listed spec hmmm...ordered new evap cover assembly and main board anyway. New main board defective, only supplies 5.2vdc to cn75 and nothing will power up on refrigerator. Put old board back in, everything works except ff evap fan. Just tested ff defrost thermistor, shows 77koh at around 32-33degrees, ok bad thermistor. Will replacing the thermistor solve my problem? Starting to get old will all my food in coolers. Thanks for any help.

I tested the old fan with a 9v battery and it works fine. Also tested the sensor on the fan assy 4.7kohm at 79 degrees which is almost perfect. My first replacement board was faulty, another will arrive Tuesday. I now dont believe the fan was bad to begin with.

Update. I tested the old board, everything tested good for voltage and/or resistance. Replaced the fan assembly and a bad ff defrost thermistor. Working good now, fingers crossed.