There has been a TSB issued for this problem, it is "TSB 08-22-97 Rev A". You can read it at genosgarage.com or any dealer can run it off for you. It's caused by a damaged hose at the speed control servo located under the battery. The way the battery tray is designed allows acid to drip onto the hose and servo.The TSB will show you a diagram and give detailed repair instructions as well as part numbers if you need any. This problem is very common on the 96' and 97' models. It should also fix the air flow problem, just like gcarlg said in a low vaccume condition it will route air back to the defrost vents until enough vaccume pressure is present to operate the baffles in the A/C duct. Make sure to put a battery mat in the tray under the battery to absorb any acid in the future, they only cost a few bucks and if they had been used from the factory it would have eliminated this problem.