Ok I have been faced with a problem. I have the dual digital controls with the auto control. No matter what setting I set it on other than 90 degrees there is no change in cabin tempt except cold. I had a buzzing sound coming from the cabin tempt sensor so I replaced it and I also replaced the passenger side actuator. Still no change.
The only times I have ever seen that condition on a GM truck, the interior temperature sensor above the driver’s head area was the cause. I assume that is the one you said you replaced so I would recommend double checking it to make sure it’s connector is properly secured and that none of the terminals are damaged in the harness connector or the sensor. Beyond that use of a system compatible scan tool will be required.