Fan only works on high on defrost as it should since it bypasses everything I think. A/C comes on at first cold, then as engine warms up hot air blows as it should (it's on defrost). New compressor comes on, A/C charge is fine, new pressure switch, new temp switch, new expansion valve.
No other controls work.
Is this climate control module under hood? Or could it be button switches on dash? Or maybe vacuum problems (wouldn't be surprised at that)? Anyone know where to begin testing what and how with amp/voltmeter and Mityvac pump? Suggestions would be much appreciated.

1980 300SD
1982 380SL
1979 300CD
1997 C220