2001 Honda Civic Interior fan doesn't work

The interior fan doesn't appear to be working at all. If I turn it to high nothing will usually happen. Rarely, it may turn on very briefly for less than ten seconds and switch off and even then it's seriously underpowered. During this time it appears as if the A/C and heater works though; it's just that the fan isn't blowing the air through the ducts. If I go 60MPH+ I'll feel a decent amount of air blowing out of the ducts even when I've got it switched off. I checked the cabin air filters and gave them a good cleaning and still nothing. I also ran the fan at high with the filters out to see if the fan itself was blowing and it wasn't at all. If I manually spin it it'll spin fine so nothing is blocking the fan from spinning. When it does briefly work it seems as if the fan isn't getting enough power or perhaps there's a loose connection. I've also verified that all the fuses are working as expected so it's not a fuse issue. Anyone have any suggestions on what I should try next or what it could be?

I'm not a mechanic but I have no problem trying new things myself. Worst case I screw something up and learn something in the process. So any suggestions, no matter how technical, are welcome! :)