Iím sorry for the misunderstanding, itís entirely my fault. I should have described the vehicle better. This is a 2004 Jaguar XJR supercharged 4.2. It has no dual heater control valve like, say an S-Type does (even with the same engine). The main difference is the type of heater core: the dual heater control valve system has three heater hoses going to the heater core. One for drivers side heat, one for passenger side heat, and a shared return line. It is essentially two heater cores in one. The non-dual heater control system has two heater hoses going to the heater core, one supply and one return. The dual zone temperature is controlled by blend door manipulation, not coolant flow.
Again, Iím sorry for the confusion. I know your time and knowledge are valuable and I appreciate you sharing a little of it with me.