I bought a heater bypass kit from www.mercedessource.com. It is designed to bypass the servo and comes with all the necessary hardware to hook it up and adjust it from inside the car. As long as you do not have any vacuum leaks and your AC works, they will work with the bypass kit.

I have had it with that servo, which IMHO is one of the poorest designs that ever came out of Daimler Benz back in the 70 and early 80's. I read in an SL book that even when new they were problematical at best. Mercedes bought the patent for the servo from Chrysler Corp who used them in their top of the line Imperial back then, but only for 2 or 3 years and went to a electrical vacumn system instead of a vacuum electrical system and NO SERVO.

Anyone out there have a bypass on their 70's SL or SLC? Coment appreciated.

Thanks!