makes sense..

The fan is 6". I read some of your posts and followed directions such as as few 90's as possible, straight lines and all is in 6" except where it exits the facility, which is an 8" piece of dryer hose.

Ambient temps are 73F.
The fan sucks out of the top on the back wall centered between the lights.
The intake "holes" are on the back wall as well and get air from an 18" space between the box and an exterior cinder block wall.

There is an available a/c duct within 24 inches of the front wall of the box at the top. Could I cut an intake off this duct?
If so is it as easy as cutting the hole and installing a straight piece of 4" duct?

Thanks for the assistance. I value your opinon.