I replaced the heater core this week. I did not remove the dash. While in there, I noticed that the foam rubber insulation material on the blend-doors has deteriorated and is crumbling. I'd like to remove it and put some new material on it.
My question is: can those doors be removed and replaced without removing the entire heater box? I know the hinge is spring loaded and if I can get them off, I don't want to have a problem re-installing them...

 

When I had my dash out I remember looking at the foam inside the heater box. Even with the box out I decided that trying to get the whole heater box apart was not worth the effort. I do not think you could put the bled door back in with the dash installed and the box on the firewall.