Hi. I am wondering what this heater valve's purpose is in my 1980 300D. I have the ACCII servo which works pretty well, but the lever broke on this coolant valve thing and now the temperature dial is a bit off - needs to be set higher to maintain heat. If the servo has it's own valve to deliver coolant to the heater core, then what is the purpose of this vacuum controlled valve? Just wondering if I should get a new one since the lever broke. It's the circular black object just to the right of the battery.



Thanks!