Not sure of the exact name for it but it's the box that houses the vane to control the air temperature from the heater. Ie diverts air over the heater matrix or straight through. If you have your dash off there is 3 boxes. From left to right, there's the blower, then the air con evaporater then the heater box diverter. I need the box dead central as my vane has snapped.
I don't need the motor servo that controls the vane, just the box