Need help identifying an un-used button and cable.

[PaRACECAM]

My 2007 Vibe has 3 buttons left of the radio. The top is AC , the middle is Recirc. for AC. The bottom is un-used and not mentioned in the manual. Un-used button and/or switch locations are common but when removing my radio I noticed this button is attached to a cable like a lawnmower throttle cable or a 10 speed bikes brake cable. Any ideas...... ?

[ColonelPanic]

The bottom button doesn't serve a purpose, it's just part of the assembly with the other two buttons... the cable you're seeing is for the recirculate switch. When you move the vent selector to defrost/floor or full defrost, this cable pushes out to disengage recirculate mode (to prevent fogging.)