560SL AC sudenly stop blowing cold air???

My perfict 1987 560SL with only 80,000 miles suddenly stopped cooling last Saterday. The car is driven only on sunny days with the top down once or so a week. Kept in garage always. The AC has until Saterday worked perfect including that tempramental climate control that has malfunctioned on my other MB cars. No apparant freon leaks, just blows unconditioned air! As the car has been cooling us on 90 Degree days with the top down until this drive am I correct in suspecting a relay? I see (2) types of relays listed : one called AC temperature relay and one called simply AC relay for 560SL. Could somone give me a direction to problem.

thanks much......