I have a 1978 300CD and the heat/ac is not working. I believe there are actuators and other parts missing and wanted a way to just run hot air to the interior of the car. I tried running coolant from the radiator to the head, to the heater core, and back to the pump, in hopes of constantly blowing hot air. But I recently found out Mercedes cooling system is backwards? Anyone have any diagrams or any ideas as to how this would work? If anybody could help in any way I'd really appreciate it.

Thanks,
-Jay