Confused on Heater Control Valve for 1975 Duster 360

don't all these cars have a heater control valve??? The AC valve was vacuum controlled and the non-AC had a manual cable? Other wise the heat would be circulating full on hot water even in the middle of summer, You would roast!
No sir, heat only did not get a water cutoff valve. Hot water circulates through the heater core at all times. The blend door is manually closed at the controller. Some owners do install a hand operated water valve under the hood. Makes the cabin a little bit cooler.