I see that this post is almost a month old, so by now you have probably figured out that the vacuum line was knocked loose from the pod controlling the center vents when the expansion valve was replaced.

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1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660