I suspect your heater and heater control is the same as pictured. 1st picture looks into cab, passenger side fire wall. Carefully observe the 3 cables running from the back of your panel to the heater box in picture. Heater core in 2nd picture - in upper left corner of heater core notice 1 of those 3 cables as it comes through firewall. Cables control louvers within heater box to divert air to DEF, AIR or Heat. 4th control level (you have 2 shown in your picture) is electrical switch to fan. Maybe orange wire.
Pretty good chance your levers are broken off. Parts are easily available and rebuild is not hard.
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Last edited by Hambone; 05/12/2020 4:41 PM.
~ HB
1966 Chevrolet K-10 | Ghost: formerly Flappy Fenders | In the Stovebolt Gallery
1962 Chevrolet C10
1962 Suburban