The 3rd floor of my house isn't cool adequate.How should I set the "flaps" on my vent to force the a.c upstairs I currently have the vent pointed in the in front of...

I currently have the vent pointed in the in front of direction that they were set for winter. Is that correct?
Answers:    During the winter you don't enjoy to worry as much. HEAT rises to the ultimate point.

In the summer close the vents down stairs as much as possible. Just hand down them cracked open. This should force more of the pressure up stairs. I own the same problem. I enjoy to use a small window element to help out up within. But I close the down stairs vents as much as I can. GOOD LUCK.
I am not sure what category of vents or ac part you have, but I might know how to help you speed things up a bit. I am sure you know that warmth rises, so it only make sense that this would be the warmest floor of the house. One of the things that you could try is, if you have a box disciple, Open a window upstairs (open it no wider than the dimensions of the aficionado if possible), then you could crack a single porthole open downstairs. Place the box lover in the pane upstairs pointing or blowing out the window. Crack accessible the single window downstairs and craft sure all other window are closed. When you turn on the fan upstairs you should create a "unenthusiastic pressure" environment which will force the heat out of the upstairs and replace it near some of the cool air from downstairs. This works really capably if it cools off within the mornings or evenings. Seal up the windows again when you realize a comfortable temperature. It shouldn't pilfer that long, and if you stand in a corridor or doorway, you should be able to be aware of a pretty good draft flowing historic you towards the open upstairs pane. I hope this helps you.