Hi Kristal. (and Joe)
If antifrezze is comming out of that hose, your heater core is leeking :-(. As joe said, its not an easy job to take out the black box but its possible. If something breaks on the job, you can use special glue used to repair plastic bumpers. I thing you can buy it in any good car repair shop. It will dry up in 5 min and you can sand it and work with it after 10 min. Anyway, you will need a loooong weekend, a new heater core (or repair it)...good luck Kristal
PS. The hoses goes from the thermostat housing and water pump to the heater core thu the firewall. The other two is for the A/C. Note you will have to "drain" the A/C fluid (only a professional can do that and you might want save the a/c fluid, its expencive and also bad for the nature..ozon layer etc..) before you can take out the box
Originally Posted by silver69
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.