Cadillac Repair: 1990 caddy, cadillac deville, test procedures

Question
90 cadillac deville ac was fine and turn ac to 68 from 74 and now blows hot air when ac is needed  all lines are cold under hood but blows hot air now

Answer
Sounds like a fault in the AC/Heater programmer.

If you are mechanicaly inclined or know of someone who is, You will need simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.