Refrigerator/Freeze not working, well bottom shelves of freezer are

I have a Whirlpool Model ED25QFXHW00, a side-by-side refrigerator/freezer. The refrigerator side is warm. The freezer side keeps things frozen on the bottom 2 shelves and everything else melts. What should I do to troubleshoot and repair? The shelves are empty, so that is not the problem. I can see a little ice frozen by the vent at the bottom, but not bad. Something is getting cold, but the air is not going up or over. I am guessing a motor or fan burned out, but I am having a hard time figuring out which ones. This is an older refrigerator/freezer but has served me well. I don’t have money for a new one, so I want to do my best to try and fix this one. Just need a little guidance.