Sounds like everything is running fine. If you push the a/c button several times you'll notice the snowflake go on and off, when the snowflake with line through it is on that turns off compressor. (kind of opposite as you would normally see in other vehicles) If you push auto ,like Mikejr said, it's just like a t-stat and keeps the cabin the temp your set at and will cycle on/off as needed. Hope you now understand the basic use of your Hummer H2 A/C system.
