Any who. I would suggest putting a small fan with less power than that one blowing air in. I bet that fan just can't pull it in fast enough. If not and if your fan is only 4" I would get bigger. But try the intake fan first. For windows man I have you solved I just had to do this. I'm way too stoned to make enough sense sorry lol. Get 2" sheet of foam insulation board, the type that looks like styrofoam with a silver lining on one side. Cut a piece to fit snug in your window frame, put in a set of light colored bamboo blinds and try to mount it as close to the window as possible. Then cut holes in your precut piece of foam board one for intake and another for Exaust if your room is very hot. Attach your duct or ducts with foil tape and install the foam board in window hole. Tape edges with foil tape. And cover the whole thing with black plastic if your that paranoid about light glowing through like I was.( im hoping you have a windowsill inside so you can fit this foam piece in the window hole. If not then just use long screws to cover the whole window frame with the foam board). Then run your ducts at a slight angle or make one bend and no light will go out. Your duct holes will be concealed behind bamboo curtains. The type that are a bunch of tiny bamboo sticks. Also want to cover the spot behind the duct holes in between the foam board and blinds with something white to match the backround white of the foam board as your looking in the window from outside.