Classic/Antique Car Repair: 1977 corvette air system, air conditioning compressor, vent system

Question
QUESTION: The air system has stopped blowing cool air.  I can't change it from hot to cool temperature.  The switch moves from hot to cool, but the air only stays hot.  Any suggestions?

ANSWER: Are you talking bout the air conditioning system or just a heater and vent system? Let me know.
Brad

---------- FOLLOW-UP ----------

QUESTION: the air conditioning system.  I have had the coolant topped off and recharged, but when you turn on the system, it only blows hot air and it gets hotter as time passes.

Answer
There are several possibilities. One, the blend air door in the heater box the diverts air from heat to cool could be sticking or the operating mechanism defective or disconnected. The second is if there is a hot water shut off valve in the system it could be defective or the controls not functioning. Is the air conditioning compressor clutch engaged and turning the compressor when the system is running? Let me know.