Yeah, I followed Parrot's cleaning the duovalve instructions. That post alone is worth registering and logging in to that forum, I have to say!
It seemed to maybe improve my issue a lot, but it is not completely resolved. I get cool air and the car cools down, but the vent temperatures are warmer on the driver side than on the passenger side. I don't have a thermometer jammed in there -- it's clearly noted just by holding your hand up at the vents.
I haven't coughed up the $100+ to pull a vacuum and get all the refrigerant out and then recharge the system, though several folks have recommended that to me. The lazy bums at the local quickie shop just noted 39psi on the schraeder valve and told me the system was fine. Grrr... Still diagnosing and waiting till I have time to sort this out.
Cheers, John