The temperature in the refrigerator rises then drops. The fan was replaced and was working properly until now. I took out the fan and pushed the blade forward . But nothing changed. Do you suppose it's the fan or control board ?
Test the thermistors on the device to see whether they are inside range. Test Range ts should be 42.2K ohms at 0 degrees, 14.4K ohms at 37 degrees, and 5K ohms at 77 degrees. If the thermistor is out of range, it must be replaced. The control board would be the problem if the fan was accelerating up and down. I inspect coils to make sure the tubes aren't blocked with dust. Also, see if the condenser fan is turned on.
If it Turns out to be a faulty control board. We can help you to repair failed control board, here is the link https://www.upfix.com/product-category/appliances/refrigerator/