Air conditioning on US cars is widely described as a dealer-added Kuhlmeister system rather than factory equipment, and its absence is repeatedly named as a reason buyers stayed away, especially in hot climates. Several commenters note AC can be retrofitted to look original if all the correct parts, including a different fan clutch, are sourced.
Air conditioning: dealer-added, and the no-AC discount
Mercedes-Benz 300SE (W112) Fintail · buying