I push the a/c button the icecycle symbal flashes a few times then turns off on 2003 Hummer H2

sometimes it stays on, most of the time it flashes then off. At first it blew hot air out the pass side & cold drivers side. Dealer said sensor and fixed that, then about a week or two later it just won't get cold a/c symbal flashes then goes out.

Asked by for the 2003 Hummer H2
have a/c module scanned for codes and post so we can adv
Finally got into the dealer they scanned a/c NO CODES.