I own a townhouse where the A/C units are under a raised deck (if the
owner has installed A/C). To get sufficient intake and exhaust flow the
owners have cut various shaped holes in the deck siding and covered the
huge openings with wire mesh which look terrible.

I had an A/C person out today because I'm thinking of putting in A/C (I
don't live there, but the tenants have been bugging me). He was not
encouraging. First, he said it was a terrible location for the units,
something I already knew. Second, he said that most of the existing
units had been put in without permits and that if he pulled permits for
a new installation then the city would see all the code violations on
the other units and make them be corrected (which is something I would
not be opposed to since the current ).

The thing I want to figure out is how to replace all these awful looking
siding panels on the decks but still get sufficient air-flow for the
units. I can't find any information on the CFM of the exhaust of central
A/C units.

The panels are about 30" x 30" made out of wood siding. I was thinking
that we could build panels with these
http://www.grainger.com/Grainger/DAYTON-Intake-Louver-5NKJ3 and paint
them to match the deck color, but I don't know if they'll restrict the
airflow too much.