@TGeissler I was not able to duplicate the sims drying issue. The fans worked every time to dry my sims. The drying would stop when I turned them off and then continue when I turned them on. I tested on an old save and two different new saves. The fans do not dry the puddles left from drinking water but that's another issue with it's own bug thread.
I had a lot of trouble trying to test the heatwave cooling. Sometimes the sim would not get the overheated buff at all with fans on, and if I turned them off, the overheated appeared but didn't go away when I turned the fans back on.
I'd have my sims stand out in the sun with default clothes or pjs and they'd not get the overheated. If they did get overheated, bringing them inside with the fan stopped the buff, but other times they'd get overheated inside regardless of the fans being on or off. I was not seeing anything consistent with the overheated debuff.
A couple threads exist for temperature effects not working properly for sims with iceproof and heatproof traits. I think perhaps the issue is more with the temperature affects themselves and not the fans, or maybe a combination of both.
Edit to add Screenshot for the drying:
