Air conditioner not turning on

[mng130]

I have a 2005 Tahoe LT with 5.3L. Was driving yesterday with the AC on, everything was working fine. Then I noticed it was starting to get hot, looked down and the AC symbol was off....Hit the AC button, it blinked a few times and then turned off again. Just kept running with the temperature control in Auto. About 20 minutes later the AC game back on.....only to go out again 15 minutes later, after which I have not been able to get it to turn back on. This is true for both manual and automatic mode. Any help would be appreciated. Thank you in advance.