Freezer stopped working Fridge works fine.

Freezer stopped working the fridge and upper ice maker works fine. Error code 40 E and 21 E. I had a "guy" come out. He said the logic board was bad. He reset stuff and 3 days later he replaced the logic board and said he was 99.9% sure that would fix it. It didn't. In fact the upper ice maker stopped working while the fridge still worked. I complained he came out 3 days later and vacuumed out the Freon and refilled the system. Still had a error code 40 E. I noticed the unit was much colder overall. The freezer evaporator iced over but the fan would only turn on for a few seconds. I ordered a new freezer fan. When I was replacing the freezer fan today I noticed the evaporator go into a defrost mode while I was replacing the fan. I tested the fan before I put it all back together. It would run for about 15 seconds, shut off and about a minute later it would run for 15 seconds or so. The evaporator is definitely getting cold enough, I saw thin ice forming while I was in there. After I got it all back together, the temp readout quickly went from -1 to -8 but the fan doesn't appear to be blowing very hard if at all. It should be blowing hard but it's not. The only thing I can figure is something in the system is not telling the fan to run properly. Any ideas?