I also have a Frigidaire refrigerator in which the evaporator fan no longer runs. We bought the fridge used, and the fridge never cooled properly. I know that I occasionally heard the fan running, but it sounded very loud, and eventually it stopped running altogether. Before buying a new one I double-checked that there is voltage to the fan, and there is, 12VDC. I replaced the evap fan motor but the new one does not run either. I had the fridge in diagnostic mode and tested "HI" and "LOW" functions and voltage is present at the connector. Also used a multimeter on both fan motors (old and new) to test for resistance and there is on both (as long as i tested the right wires).
(side note: I'm not sure if this is how it works, but there are three wires in the connector, my guess is that one is for Low speed, one is for High speed, and one is the ground. When i tested the voltage, there was 12V on both wires for the different speeds regardless of what speed setting i had the diagnostic mode in. Is this how it is supposed to be, or is this maybe the issue?)

Any help anyone has would be appreciated.