Final answer:
Both Technician A, who mentions that a temperature blend air door regulates air bypassing the heater core, and Technician B, who says that the recirculation blend air door controls fresh air, are correct.
Step-by-step explanation:
The question is addressing a concept within automotive technology, specifically the function of air doors within a vehicle's heating, ventilation, and air conditioning (HVAC) system. Technician A states that a temperature blend air door controls the amount of air that bypasses the heater core. This is a correct statement because the temperature blend air door indeed regulates the mix of hot air from the heater core and cool air from the air conditioning (or outside air) to maintain the desired cabin temperature. On the other side, Technician B claims that the recirculation blend air door controls fresh air, which is also true. The recirculation door determines whether the air entering the HVAC system is taken from outside the vehicle (fresh air) or is recirculated from within the cabin.