Ford Repair: AC, air blows, hoses

Question
hello, i have a 98 navigator. i have the following problem with my ac: the unit will come on, the hoses ice cold.  however, only warm/hot air blows inside the car. any ideas? what should i test/check?  Thanks for the help!

Answer
Hello and thanks for the question...I'll try to help.
 It seems that the blend door, that switches from hot to cold isn't switching. It is located in the evaporator case and is driven by a small electric motor. I would check that first.
 I would also make sure that the system is FULLY charged.
Hope this helps,
Erik