5KCS Climate Programmer Q

[Steve Sherman <Steve.Sherman@nsc.com>]

The Climate control programmer (the thing with the vacumm valves and
motor) is a bit flakey in my 87 5KTW.  The symptoms are the usual air
thru the defroster vents, but it only seems to happen when the temps are
hot.  If the air temp is 65F or less all is well.

I plan on fixing this, and was wondering if the temp sensitivity should
give me any clues.  Any BTDT's out there.  While I have a replacement
programmer, I would like to just fix one vacuum switch if that is
possible...

TIA