2016 Yukon cabin temp control issues

[LD Dirty Shame]

My Yukon has developed a temperature control problem with the heating and cooling settings.   First issue is when A/C is not needed.  Since it's winter, I can start my drive, typically it's 30 or 40 degrees outside, wait for the engine temp to start to rise and ask for 74 or 72 degrees from the previous days drive.  As soon as you hit or turn on the FAN control knob, A/C selection comes on.....but I don't need it.  It's 30 degrees outside!  Took it to my GMC dealer, and he can't find any "error codes", nor can he duplicate.  So I provide him with 3 or 4 videos from my iPhone.  It clearly shows the engine temp starting to rise and able to give "warmer" air than the outside air, and outside temp on the touchscreen at say 34 degrees.  A/C selector clearly comes on when pushing the fan ON and either vents or floor selected for my air.  Been to him twice.  Then, it has progressed to really HOT air coming from the vents or floor, when set to 72 degrees.  I set a little temp gauge in the vent and when asking for 72, its pumping out over 100 degrees.   Sent him a video of that.  Drove down to the dealer on a half hour drive with it set this way, and showed him...."yah, that's sure hot" is his reply.  Now, on longer trips of 3 hours last weekend, we are either too hot or too cold.  One point we had 69 dialed in on both passengers, feet were cold at 69 but dash vents with my thermometer was near 120.  Settings never seem to track.  You can set  it for any temp and it starts out comfortable, but slowly starts to get hot, then you crank it back lower and then we are cold. He has had it again for two days and can't duplicate on their test drives.  Says he can't do any "warranty work" without error codes being generated.  Oh, and the other really strange thing.....three months ago, my rear window completely blew out.  Exploded like it had been shot out!  And we were driving down a road at 15 mph.  Course, it has a REAR DEFROST button on my dash, where all this problem is occurring NOW.    Wonder how I can help my dealer find a solution?  Yukon has only 18k miles and purchased new from this dealer.

[Tahoe02]

I had similar issues with my 2015 Tahoe and they could never figure it out after multiple attempts. I documented everything and ended up doing a Lemon Law case in Florida which I won.