[Lee]

On the LTZ when you have the climate controls set to auto, the AC compressor will always be on when the outside temp is above 40 deg.
Page 3-25 in the 08 manual will explain the automatic climate control.

 

[Lee]

Even if the A/C light is on... The compressor is not actually running.

I know it sounds odd, but the manual said the compressor will be on when the outside temp is above 40 deg. F.

 

[Lee]

Hmm... I thought it shut off the compressor. Your probably right though. You quoted the manual, where as I am just guessing. Lol
I know it still blows out hot air though, so... does it just kinda make the compressor "waste" all its energy?

Don't have a clue how it works

 

[Lee]

So if it automatically comes on when it's 40+ outside, why has mine been coming on at -20f ??

Sounds like yours is not working properly.