So I'll say that 4-5 months ago I had an issue with my internal blend door. Basically no matter what I turned my cool/heat dial too it was burning hot air! Somehow the door was stuck open (or maybe closed?). Now it seems like no matter what I do I get the air temp of whatever the outside air is. Though I can make it colder if I hit the AC button. I can't get any hot hot air unless it's warm outside, even then the air is only warm. I do not believe it's the heater core b/c I don't have any condensation inside my car and nothing smells in there. I checked the engine coolant and the reservoir seems fine. (It's a VW Passat so I don't see any way to check the radiator, only the reservoir bulb). I'm wondering if the blend door got re-stuck closed (or maybe open?)?