Is it possible that the flap door inside the dash of my 94 C220 could stick during hot weather? If so, what part is actually sticking? The car will not blow a/c out of the center vents when it gets hot outside. I have to run it on ec for about 5 minutes, and sometimes back and forth from ec to a/c before it finally starts blowing from the center vents. When it is not too hot out the system works perfect!

Thanks for any ideas out there! Your input is greatly appreciated.

Michael

94 C220 132,000 miles
89 300SE 118,000 miles

Very common failure is the **fresh air** flap diaphram. By operating the system in ec this diaphram doesn't receive vacuum. There is a vacuum distribution block that sends vacuum to all of the flap diaphrams, have the vacuum diaphrams tested for leaks there. The vacuum lines(2 stage) that operate the fresh air diaphram are dark red & green with blue tracer.

The diaphram's check out OK. The problem only happens when it is hot outside. Any other ideas?

Thanks!