Mac mini (mid 2011) fan at full speed constantly I upgraded my Mac Mini's HDD to a new SSD... Since then the fan has been running at full speed constantly. I placed back the old drive but that did not fix the problem. I also tried using SmcFanControl but that does not work at all.

In addition, I reseated the fan connector just to be sure, still no joy. Can anyone recommend another option? 

I'm running Yosemite...
check the thermal sensors. I broke one off of my Mac mini trying to upgrade the HDD and the fan ran at full speed since. I had to replace the Logic Board to fix the problem.