AC blend doors sticking partially open heater control valve sticking open blend doors foam crumbling

When one of these old Mercedes have been sitting for many years and you start up the blower little pieces of foam shoot out of the vents that are for ceiling the blend doors
This will cause unwanted core air to bleed by or outside air
Doors partially not fully closed or open will not allow your evaporator blend doors to fully open or close
On this model when the heater core control valve leaks or stick open, you have hot air in the HVAC case that will not allow you to have your cold air