What is the left knob above the radio for?



It seems to be broken since the "D" shaped rod doesn't connect with the knob.

The middle knob is for the lighter and the right one is the 4 way flasher. The defroster switch is down below the radio. Also, the knob labeled Defrost turns on the A/C compressor and fan. Why is it labeled Defrost? Is there a switch just to turn on the fan for heating without A/C? What is the position of the 4 levers for max A/C cooling?