cable on side of heater duct

[blwhite]

trying to figure out where the cable goes that is hooked to the side of the heater duct on my 1984 CJ7 . it is the one on the right side of the part of the duct directly in front of the passenger's seat. none of the knobs/controls on the dash seem to affect it, yet it has a cable hooked to the side of it running up under the dash. i am unable to trace the cable without taking the dash out. The part it seems to be there to control is broken.

any help would be appreciated.

thanks,

 

[elwood blues]

That cable is connected to the off/heat/vent cable. If you pull that cable full out, it pull the cable you are reffering to, to open the fresh air bypass.