I would just add that Autotemp 1 vehicles started as early as 1967 or 1968 through the 1970 models and they are usually not fixable because parts for them (especially the controller in the right kick panel area are no longer available). Autotemp II systems are readily fixable because parts are available for them since Mercedes Benz bought the patent rights for the system and improved the quality of the controller. Because Mercedes Benz has a strong policy of supplying replacement parts for most all of their historic models, Performance Analysis Company still makes the controllers as new again that match the improved Mercedes systems, so we can get everything we need for these systems going forward. The Autotemp II plus systems that started with the formals in 1974 were quite problemmatic and parts availability for them are also an issue. So the 1971 - 1973 models are the only realistically fixable systems.