My air is cool part of the time but not all the time. What could cause this?

What is your question?

I definitely notice more on long drives. Cool for the first half (approx. 2 hr). Return trip is more warm then cool. Next day get in a go and will freeze you out again.

What makes this problem better or worse?

When engine is warm or in town with lots of stopping and starting

How long has your 2010 Hummer H3 had this problem?

We bought about 6 weeks ago and has been since we purchased it. Of course not until after we purchased it.