You need to T a vacuum gauge into the system and monitor it to see what is going on when it doesn't shut off. It could be that you tested the green climate control line when the climate control was in a certain condition and then when the climate control goes into another condition a vacuum pod leaks. I'd simply block off the yellow and green for a while and see if everything works fine. If it does, then hook one up and test it, then the other.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13