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I just picked up my 1995 c4 that hasn't been on the road for 10 years, i got the digital heater control to start working now it won't change from defrost to the floor. my question is how much vacuum is on that system and how much will it take to move the dampers?
Realatively little vacuum is needed. The engine produces enough at idle to operate the system. Their is a vacuum check valve on the passenger's side of the engine that is well known for failling and causing the symptom you describe.
do you know exactly where it is i looked and can't find it
It is under the cover between the manifold and valve cover. It's a black cylindrical valve with one tube on one end and 2 on the other. See attached pic.
After checking that, check the vacuum lines (all of them) to ensure they are not kinked or cracked. The lines at the cruise control servo will literally rot to dust.
If all that checks out, then your issue is most likely the controller under the dash, driver side. I bet money that's it and it is an absolute exercise in patience and dexterity.
vacuum question
