WTF? Led case fan, light up with no power?

I took out some LED fans to clean them.
I shot full blast of compressed air on to fan blades and they spun to full speed and the LEDs lit up like it was getting power.
LOL i didn't know it could do that.
Where is LED getting power from?
I thought LED need power from PSU?
cuz my Antec PSU has some 4 pin connectors what only has two wires connected and it says fan only, if I connect LED case fans to that, fans does spin but LED doesn't light up.
lol

I think I know what happened. A motor is basically a generator running backwards, so when you blasted it with air the motor span and generated a voltage, which was enough to turn on the LEDs. I think you were lucky to spin the fan the right way though - if you did it backwards then the voltage may have been enough to kill the LEDs.

Yeah I noticed the same thing when i cleaned em wiht my blow dryer. actually i tried both ways and the fans still work fine

Actually, that may of been away to get past having to put them on a 4pin to be bright maybe? Just get most of there power that way.