C32 AMG Airconditioner is intermitent. Sometimes it cools and sometimes it doesn't. It doesn't act like the R134a is low where the compressor goes of and on. When it cools it cools REAL good. I can drive around most of the day and the AC works fine. Then next thing you know its blowing hot air. Appears to me that a sensor isn't working to tell the compressor to kick on. But I don't have the fogiest ideal were to begin because it's do intermitent. Any Ideas any one?