Two technicians are describing heater diagnosis. Technician A says one heater hose is hot to the touch and the other hose is cold when the heater core is functioning okay. Technician B says the upper radiator hose should be at engine operating temperature, which is very hot to the touch. Who is right?

ASE defines area A7 heating and air conditioning as an individual service area. This area includes all components and systems both mechanical and electronic that are related to a vehicle's heating and air conditioning system.