Just thought I'd chime in that I had this happen to me today, I drove to work and HVAC worked fine, returned home and the thermostat display functioned perfectly, and I could hear the vent actuators opening/closing, but nothing produced airflow. I checked the fuses, (and unplugged one which ended up scaring the pants off me when I heard all the bells go off, and the rear ride actuator engaging continuously LOL) and nothing displayed a problem. I supposed it to be the FSU. An hour later, I decided to play around down there since it's easy to get to, and I removed the floor paneling to find the FSU and a fully enclosed blower fan. I thought "well damn the fan is completely sealed. HOWEVER!... There is a "trap door" (my terminology) that is about 1.5inch x 1.5 where the two wires from the FSU lead to the blower motor. At first I didn't want to remove it, so I tried reseating both FSU plugs and restarting the vehicle. No dice. So I decided to open the trap door. Inside you can see the blower motor in all her naked beauty, and you have access to the core, where the magnetos sit (which will spin when alternating currents are applied). I said "this is potentially dangerous, and costly; so let's do it!"... I unplugged the motor from the FSU and removed the key from the ignition. I REPEAT YOU NEED TO DO THIS UNPLUGGED, THE LARGEST AMPERAGE FUSE IN SERIES WITH THE MOTOR IS 40AMPS WHICH IS MORE THAN 80x ENOUGH TO KILL YOU! Safety first! I then took my pocket knife (probably should have used something non-conductive since magnetos can capacitate energy), and gave the magneto a 1/2 total turn. Low and behold, when I placed the key back in, it began turning as good as new, if not better! I cycled it a few times, and at variable loads, and it is perfect! I thought I heard some debris get blown out, unsure, but if it did it was very small particulates.
Since it is winter, and I haven't ran the AC in a while, I continue testing it while in MAX AC mode for about 15 minutes to cycle the AC as well (which you should all do if the AC will go a prolonged period of inactivity).
So long story short, if the fuses are good, unplug and give the motor magnetos one half turn and try it out; if you encounter the same problem. If it still fails to attempt to engage, then it is most likely the FSU 90% chance. OEM price is about 110 for this, so try the free easy way first.
That had to have been the smoothest tinkering attempt I have done with this car.
Only time will tell if something permanently fails, and I will repost if it does.
Rock on!