4028 is running the wrong way?

I have installed this fan from RatRig, used the red and the black wire and the blue for pwm control. When I start using my printer (V-Core 3.1 with an Octopus V1.1) I noticed that the fan turns the wrong way so the air blows out at the top. Is there a solution to make it turn the other side, other than flipping the fan..?
And can the yellow wire be used for anything?