I have a 1999 F-150, 4.2 6cyl. Haven't used my a/c for two years. I 'm no mechanic especially on these newer vehicles so I charged the system today with a diy kit. The chincy meter showed 35 psi. Everythig was fine and blowing cold for about 5 minutes then started blowing hot in an instant. I don't think I touched any controls so I doubt a broken **** is possible. The compressor appears to be running constantly and the metal line with the Low inlet stem valve is cold to the touch so there is refrigerant in there. It's just stopped blowing cold in the cab.
Any ideas where the fault may be and how I troubleshoot it?