So, I've owned a 2006 Chevy Express van, 2011 Chevy Express van, 2010 V and 2013 V. All have the identical quirk in the AC. It runs ice cold for 2-3 minutes and then has 10-15 seconds of warm. Then it's back to a few minutes of cold. All 4 vehicles did it the exact same way. Theories? No other brand of vehicle I own or have owned does this.