From what I see it a big job to remove the heater, with ac to disconnect and all the dash work. is there no otherway to get to the blend door? If the blend door is broken why is it that when you turn the heat selector to cold it gets cold, or halfway and you lose 1/2 of what you have? Is there someplace I can get a print of what the heater housing looks like?
How much movement should the door have? Can I tell by looking at the actuator motor shaft if the door is moving all the way? It looks like aluminum shaft with a flat side about1/2" around. On cold the flat side is at about 11 o-clock on hot it moves to about 5 o-clock. Is is possible there is something in there not allowing it to go all the way? (I think something might have fell down the defrost vents) If I could find a way to to view it before starting a large task that would be great, or if I could clean it out somehow. and yes I'm willing to drill a hole if need be into the housing to see the problem.
The picture you sent, is the actuator motor located on the bottom of temp blend door?