Likely Heater Core Failure

[HIZNHRZ]

Originally Posted by GOLDCYLON

Use this as an oppourtunity to clean the vents or consider a dash leather wrap upgrade opportunity . Repair the foamy felts that surround the AC vents. I used to joke about the heater core being GM part 000000000001A and then the GM guys designed the rest of the C4 around it. Some GM Engineer is still prob laughing his AZZ off. GC

The statement above in bold and italic's didn't mean much too me when I first read it. GC, now I understand exactly the point you were making!