I found the solution of my A/C. It is the compressor that always on and not cycling. If you believe the Haynes Tech book, I need to replace the cycling switch.
My question is: Do you have to discharge the AC/C to replace the cycling switch ?
no, you do not need to drain the A/C. Just unscrew the switch, it has a protective (shrader Valve) looks the same as your tire valve for putting air in your tires.You wont loose any gas.