A/C Indicator

Have an '92 Chevy Silverado..I have a flashing A/C indicator when I try to use A/C...It will flash for a couple of minutes then it quits blinking..My A/C worked fine until then...This has happened before..I can make it stop (for a few days) by detaching and reattaching my negative battery terminal..I had A/C charged 2 mos ago (had pressure test done with no problems)..I have changed out A/C -Heater-Defrost controller as well in dash..Is there a sensor that is flakey that is causing this and can it be detected by a code/diag tool?....Thanks,Pete44