I have a 2011 LTZ. Have had it to the dealership more than a dozen times for various issues. This last time was for no heat coming out by my feet. Got it back, surprise surprise not heat still. Now when I change modes it makes a crunching sound. Also, the fan speeds and temps change on their own. When the heat is on high the dash outlet gets so high it can burn your hand, but when you turn it down one click to 85 degrees it is marginally warm at best. Any thoughts?