Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
The problem is due to a worn drivers side temperature actuator. The worn actuator can travel beyond its normal limits. When this occurs, the system goes into a default mode (full heat). Replacing the drivers side temperature actuator will fix your problem. Copy and paste link below for video documenting location and replacement procedure for the actuator.
The drivers side actuator is the one under the dash as shown in the video. It is located under the center of the dash and is most easily accessed by removing the panel under the passenger side of the dash which extends under the center of the dash. Part number is ***** Delco 15-72971. After installation of the actuator, either remove the HVAC fuse or disconnect battery for 30 seconds. Reconnect then start engine, do not touch any a/c controls for one full minute while the system automatically recalibrates.