So you are saying that the portable A/C has 2 intakes? Both pulling air from outside the grow area? Where is the exhaust? I'm missing something here.
An Ac unit runs of the phenomenon that if you squeeze freon gas through a set of tubes that allow it to change from gas to liquid based on the size of the tube you can essentially move energy from one side of the tubes to the other because of a property all subtances have called a phase change.
The hot side of the coils is cooled using an independent fan. The intake for the hot side and the exhaust for the hot side run freely of the cool side. This means that the coil is cooled without ever causing a draft or pressure change or leak to the room.
The cool side of the coils also has an independent fan sucking air from in the room past the cold coils and back into the room. The cold air intake and exhaust are both in the room on the unit.
With this AC system C02 can not escape.
Perhaps a picture can best explain it.
A portable AC that will work and can be used while the room is being enriched will have two separate exhaust and intake ducts only to cool the hot side. These units work similar to a window unit. Imagine that the red arrow on the left of this picture is completely ducted outside using two ducts.
