Vintage Cars: 1972 350SL W107.044 heat control, heater control valve, vacuum system

Question
Car is new to me, no documentation.  A/C works great, heat comes through at drivers feet when heat is off.  I have learned the heater control valve (vacuum driven) is one possible source of my problem, but when the AC is on, the heat on my feet goes away.  Is the vent at the floor also run by vacuum system or manually via the dual up/down levers in the center console?

Answer
Hey Brad, got the same guy form peachparts ( lol)
to further explain the levers control 2 small microswitches that energize the valve on the fire wall , if those are stuck open the heat is always on, the flaps that close when AC is on is directed by the AC control knob.  I can send you a diagram that may help , send to the email I provided