rear ac

If you have the airflow button instead of the rear/aux AC button is because your Tahoe has the wrong HVAC controller, it has the "truck" version which does not have rear AC. You need to go and by the correct HVAC controller with REAR or Aux button. I did that in ebay I bought a used one in 40 USD. With the good controller then you will be able to use your rear controller (RSE) too. Regards