On my 77 300D, the heater control runs full temperature all the time. The fan and air control seem to work right, so I have some control by the speed of the fan. I can defrost and direct heat out the bottom. My only complaint is when I turn the fan off, heat is still coming off the heater and it is noticeable on a warm day.
My question is: If I install an old style heater shut off valve that is run by a manual choke cable, will I have adequate heat control?
Since I only paid 300 bucks for this car, and I am planning to give it to my sister-in-law, I don't feel like dumping a bunch of money into repairing that Mercedes super whizbang dial in your heat unit.