Econoline erratic heater ducks,

When your heater controls on your e150 e250 E350 are not working right, changing from defrost to feet to dash it's all controlled by vacuum and you have some kind of a vacuum problem. The question I had was where does the hose under the dash headed to the motor go why does it disappear. Well that's where the vacuum canister is and a check valve this video is to show you what you can't see so you can figure out how you want to fix it 🤷🏼