2014 LTZ heats the cabin with temp all the way down

[Campier]

2014 Silverado LTZ Double-cab with an automatic climate control, including seat coolers. On a temperate day, I might be driving with the vents set to "face" and the controls dialed down to the lowest temperature. The fan is at some moderate setting. I just want some fresh air drafting over me. The automatic controller usually dumps heat into the cabin. It shouldn't be heating he cabin. I don't want to drive with the air conditioner on. That's pointless when it's 65 or 70 degrees F outside. Sometimes, I will toggle the air conditioner button on for a minute then turn it off: I am hoping that the climate controller will get the idea that I don't want heat. Hopefully, it will force a change of state in the climate controller.  I don't know if that is a reliable "method". 

This isn't like the old days when the occupant is actually flipping engine vacuum valves from that high leverage control slider on the dashboard.  I am sure that the climate controller is operating that vacuum controlled door and dumping heater core heat into the cabin. In my moments of torment, I fantasize about putting my own valve in that vacuum line and overriding the vacuum bellows.  I'm going to the dealer for an oil change next week and looking for ideas. Happy holidays, everybody.