[Salestax]

REPLACE THE CONTROL HEAD!

This is a common problem with control heads both manual and automatic on H body vehicles. There arent any real 'user servicable' parts inside there, just resistors, capacitors, and a silicone chip that holds the logic for the 'programmer' (this controls your vents). You'll often find that your cooling fan(s) may run while this is inoperative as well.
New, they can be pricey. Last one I bought was used for about $65.00