The AC works but while driving the air flow will switch from the vents to the defroster. Still blows cold air but the control panel seems to have no control.
You have a vacuum problem. Sounds like the vacuum hose to the switch is hooked up if you can get air flow to the vents at idle or coasting. I would check the line to the vacuum canister. And just check all the vacuum hoses under the hood for cracks and make sure they are all hooked up.
