I have recently purchased '90 s4. It has a few problems but I think I can deal with them. The previous owner removed the a/c pump drive belt and my question is, can I remove the entire a/c system without affecting the heating system? I live in the Pacific Northwest and it rarely gets hot enough to justify a/c. Also, the air pump for the EGR and its related system I would also like to remove. What other systems will be affected should I do so? I'm just trying to get rid of some of the underhood clutter.

 

Search for air pump delete, and you should find several threads about removing the air pump that supplies the fresh air to the cats.
Don't know about removing the A/C system, abviously you could remove the pump, condensor, drier and lines fairly easily, but the stuff in the cabin may be more dificult. If you ever take a trip south in it it may be worthwhile having. Also if you ever end up selling it in the future, not having the A/C parts may limit prospective buyers. For a track car I wouldn't hesitate, but for a street car... well, that's your decision.