AC Controller Q

[Steve Sherman]

One of my 5K's is giving me fits in trying to fix the AC Controller (the
vacuum switch part).  The symptoms are the usual air coming out of the
defrost vents when it should be at the dash vents.

In the past (with other 5Ks) this has not been that big a deal. Yet
nothing I try on this car seems to work for long. I have tried a couple
of controller boxes (both have been checked for hose leaks internally).
I have checked the lines between the controller and the right vacuum
actuator and they are good, no leaks and they do pass air.  The vacuum
actuator does work (will move when vacuum is applied).

When I work on the system I can ususally get things to work before I put
the under-dash back together, yet a day or two later it is back to not
working.  The only thing I have not  checked is the actual vacuum level
at the controller.  Anyone know what vacuum should be on the black
"input" line at idle???  However since other vacuum actuated things seem
to move OK (like the air recirculating door) I have been assuming that
the vacuum level is OK...

Any ideas of where else to look on this one??

TIA