syoo8

Hi everyone,

I am in the middle of changing HVAC diagrams (courtesy of Roger Tyson.)

I've changed three diaphragms and three solenoids, and voila I have no vacuum leak at the point at which the black line (vacuum source) connects to the diaphragms.

However, when I check the black line going into the firewall (near the vacuum splitter) I get vacuum leak.

Does the black line go directly to the HVAC solenoid?

If so, this means I have a leak in my line somewhere, right?

westija

The line comes from the "4-way" close to the brake booster at the engine and "feeds" the rubber distribution manifold that connects all the inside components (solenoids and the diaphragms after that) which is behind the central console where the solenoids are. I had a vacuum leak at this distribution manifold twice. If I recall correctly, it is was either quite expensive or no longer available, so I bought them from 928 International.
If the manifold leaks, even with tight solenoids, it won't hold vacuum for the actuators.

Other option could be the black line itself. Plug one end and apply vacuum to the other, without anything connected to isolate it as a root cause.

Dwayne has an awesome write up, in case you are not looking at it already, I strongly recommend. That is what I used and found various leakages

Good luck

MainePorsche

Lift the black plastic cowl that's just beneath the wipers. My vacuum (source) line had a rubber connector and was 're-joined' after it went through the first bulkhead of the firewall. This rubber connector had a big tear in it. Have a look.

syoo8

I found the problem. It was the little rubber elbow joint that connects the black source line to the 5-way splitter that connects to each of the HVAC solenoids. It was leaking. Thank you both for your help.