air con unit connections

[kanuno]

hi people
ive just joined your excellent forum which has been a very useful source of information for problems ive had on my a4. however i believe i have a problem which hasnt yet been answered in a thread so hopefully with all your people's knowledge we can solve it for me and others who come across this problem.
anyway basically what happened is i had a problem with the air con unit display intermittantly not displaying anything. there was a thread on here how to fix the problem and i did fix the problem however i created another one. when i put the unit back in the display was on and that was working however the rest of the aircon wasn't. the small motor that sits to the left of the unit runs but nothing else does. when you try to turn it on this motor springs into lift and also i can hear a motor further in the dash trying to turn one way then the other over and over again getting quieter each time until you can't hear it any more. i took the unit out and the only thing i could see wrong is the brown plug in the right corner of the picture wasn't pluged into anything. i know the four other connecters in the picture plug into the back of the unit but i have no idea were this brown plug goes unless it isn't meant to be plugged into anything? if anyone knows were this plugs into or if a thread already covers this i would be very greatful for the direction

[a8 tech]

It looks like a heater vent led light connector

[kanuno]

i didnt think the vents have led lights in them

[barking71]

i too have this bown wire unconnected to anything
the lights for the control on the left side of my aircon unit do not illumintae could be that

do you have a picture of the rear of the air con unit

also i have no power to my diagnostic port and i initially though this may be the power supply for that but unsure

any help appreciate d

[barking71]

have looked at soe wiring diagrams and this appears to be a conector for a factory radio that links into the alarm/central locking system