Ok there's a harnes the plugs into the ac control, but also there's a harness the run out of the unit. does that plug into a blue connector near the steering column? I have a S4 non turbo if that makes a differecne.

 

The ac control is the logicon. It plugs into the instrument panel harness. The AC unit also plugs into the instrument panel harness, but over on the right side behind the glovebox. None of it is near the steering column.

Look in the online manual for the S5 cars (89-91); it has a much more complete section on the heating and AC system and how to troubleshoot it. The S4 manual has almost nothing.

 

Blue and Orange connectors on the steering column indicate airbag harness...

 

Hmmm... I have an 88 base model... no airbag.