Originally Posted By: DaveL
Check to see if your furnace has a fresh air duct , if so block it off only for using the AC

Heh wink

Furnace is in a small closet.
Behind the furnace are 3 registers,
one opens to the outside,
the other two open to the 2nd story crawls space,
which also vents to outside.

The AC is portable , attached to window.

Sealing the closet/door is working out .