Near the strut tower on the passenger side is a canister with black insulation on it. There are 2 pipes coming from it. They may or may not have a protective black plastic coating. They run to the front of the car along the passenger side of the engine. Between the Engine and the inside of the fender, coolant recovery tank, and battery. They're aluminum.
If these get cold and moisture condenses on them, but you still don't have much cold in the car, it can be a blocked evap core or a stuck/busted/faulty airmix door. Since you have the code for the door, that'* likely your culprit.
I'd suggest checking for what I mentioned, and if it'* cold, but not in the car, get Chilton'* #28200 from whatever auto parts store in your area sells it. You're really going to need it for this one. Should run you about $15. There are some posts here on replacing the airmix actuator. Try a search and read up to prepare yourself for the work.