I am restoring the A/C evaporator box on my early production (December 1968) convertible, and I noticed some differences in its design compared to later production evaporator boxes. Besides the orientation of the evaporator coil inlet/outlet tubes and the shape of their gasket, I noted a difference regarding the mechanical design for the damper arm (bell crank) that would be actuated by the servo control switch. The earlier design appears to have the damper arm secured at a fixed point in its rotation by a piece of coiled wire with a short length of straight wire extending beyond the coiled portion that is clamped in a bracket such that the damper arm is located so far away from the servo control switch that it is beyond the range of the servo control switch piston to contact it. My questions are (a) why is the damper apparently locked in a fixed position, and (b) why is the servo control switch installed if its piston cannot produce rotation of the damper arm?