If the a/c unit is put in an actual window in the actual grow room, you will light up the outside with with your growlights through the unit. Keep that in mind! Now lets say your grow room is about like mine, 5x11x8 and is part of a bedroom. If you put the a/c unit in the wall of the grow room and the back of the unit is exausting into the bedroom, the bedroom will get to OVER 100 deg. farenheight!! if your exausting out back into the bedroom, you create a cycle and will overpower the unit. Ideal location for the a/c unit is in a window in the room that houses the grow room. Cool this air and than allow an intake to pull the cool air into the grow room. Exaust the air from the grow room out into the attic or somewhere else if you can, other than back into the room. I have built boxes onto the back of the a/c unit to trap the hot air and exaust it through fle pipe before and it would work for a day or two but fail eventualy. Also keep in mind if it is cold outside the a/c unit will produce steam and be a bust..(why is that person using an a/c unit in March and whats that light coming through it??) NOT GOOD!!...lol