Joined: Feb 2005
Anders is right, that small hose is the condensate drain line and to answer your question more directly the heater core and air condition evaporator core share the same black box under the dash on the passenger's side. I will tell you now - this is not an easy job and best left to someone with lots of experince on ford mustangs. Those heater/AC boxes are not available and almost all of them will have serious deterioration from old age so be careful who you take it to or if you repair this yourself. to do this witout breaking the box you will have to have most of the dash loose and unbolted - just so you know.