02 Chevy Tahoe No Front Heat

I have a 2002 Chevy Tahoe. It has the dual climate control. The heat is working great. The front is another story. It will only blow cold air. The fan works fine as far as the blower control. The settings control as far as defrost, face, feet, floor, ect. seem to be working as it should. But no matter where the temperature control is set at hot/cold no change there. Still blows cold. As I said the front only. The rear heat is working great as it should. Help. Thank you in advance.

Sounds like an actuator issue.

Could be a bad blend door actuator or the heater core.