On Mon, 22 Jun 2009 22:18:03 -0500, cjt
wrote:

Ashton Crusher wrote:
On Sun, 21 Jun 2009 12:36:16 -0400, Ron Hardin
wrote:


Cover part of the downstairs ducts to cut down
airflow.

I'd just lean something over them, but a wife may
want you to unscrew the grill and put the blockage
under it for neatness, when you get the size
right.


Blocking too much of the airflow will screw up the ac unit by reducing
total flow across the evap coil.

Parsing that sentence leads me to the (I believe correct) conclusion
that as long as you don't block "too much" you'll be fine.

Yes. But you need to put gauges on the system to find out where "too
much" is.