Couple more point my dealer tech told me about:  Hillfarmer, I thought you wanted to run Auto control. If you want to run manual controls don't run Auto mode. Dealer told me the A/C will run colder if you run manual. Then you should be similar to running a cable controlled heater valve. Yes, I have changed the heater control valve under the seat. I have not changed one for a long time now. I believe the updated valve is better. In auto it just takes a little time for the sensors to take readings and get caught up with the change. the sensors are located under and behind the seat. Lot of air to move to get air temp back there to change.