I Have A 2004 Gmc Sierra Denali With Climate Control/heating And Air Conditioning System, All Summer The Air Conditioner Would Only Blow About 22 Degrees Colder Than The Outside Air, I Put My Gages On To Check And The Pressures Were Normal And It Was Condensating Properly. It Is Like There Is A Damper That Is Either Not Opening Or Closing All The Way Allowing Heat To Enter Across The Evaporator Coil. I Think There Are A Number Of Sensors And A Separate Computer For The Climate Control, But I Don't Know Where They Are And How To Check Them. Help From Anyone That Knows About This Problem Is Greatly Appreciated