I agree with the below a small window unit(thermostat controlled)
sufficient to cool room with supply closed will keep room at a steady
temperature and can be chosen for being quiet.
A steady sound such as the ac fades into the background and also masks
sounds from other areas. Cost and time would probably be less than
installing return and possibly additional supply. Small efficfient
acs don't pull much current so that is not likely to be a problen
Stan



On 19 Aug 2005 16:00:12 -0700, wrote:

I assume you've verified that all the ducts are connected correctly, ie
that none has fallen half apart from tape drying out, etc. Also make
sure any balance controls on the ducts going to the warm room are fully
open.

In addition to adding a return, which should help, there are several
other alternatives. There are booster blowers available that can be
inserted into a supply duct going to the area that is too hot. There
are also booster fans that can be placed over the vents. This type
senses when the air flow starts and turns itself on. I've tried the
first type and it definitely helped, though it's not fully effective.
Finally, you might want to consider adding a window unit to the room.
Of all the solutions, that one is guaranteed to work.

Usually this problem is the result of incompetent installers who didn't
run enough duct or return capacity to the farthest areas. And as
you've figured out, completely fixing it later isn't easy.