you don't have to take the dash off. Look to the right of the brake booster. You should see the vacuum lines and where they split off and go into the dash. One of those supplies vacuum to the a/c components. That is the one that you want to start homing in on. That pink thing is a vacuum element. Now you have to find which one is leaking. If you pull the glove box out you should see at least one more behind it. Remove the kick panels under the dash and the glove box and start testing them.

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Jim