So they evacuated the A/C system, removed the plate that covers the valve, removed the old valve and cleaned out the valve chamber, installed the new valve, replaced the cover plate, and recharged the freon in the system. And now the A/C produces cold air at idle. :) The whole repair cost just over $200 including the freon recharge.
I never would have figured this out if sweetmusic_27 hadn't been out shopping for a new used car which led to me doing some browsing about Five Hundreds. Some things just work out... :)