Squiral under the dash

This is one of the air door actuators operating improperly. You have to determine which one. Try putting your heater/defroster in all its phases i.e. floor, floor-vent, defrost, hot-cold to see if you can isolate which actuator it is. Then you can replace it more accurately. Be advised, you may have to remove the entire dash to do the job of replacement. here are some shops if you need them https://repairpal.com/chevrolet-repair-in-prim-arkansas

it the blend door motor you can replace it or just unplug it but if u unplug it will be stuck ether fresh air or rec air