DISCREPANCY -Low RPM grinding noise from behind HVAC controls inside dashboard.
CAUSE -Gears stripping inside Temperature Control Valve (TCV) actuator because TCV will not stay in the 12 o'clock position.
BACKGROUND -Removed A/C actuator from the shaft of the TCV, see photo #13. Rotated TCV shaft by hand to the 12 o’clock position constantly applying a twisting effort. Once I released my grip the TCV immediately swung back to the 6 o'clock position. Feels like something is missing like a counter weight or tension return spring. I inspected the air box and found no debris which would prevent the ’04 TCV from fully opening. I was hoping to find a ROLEX watch or diamond ring resting a top of the TCV flap but no luck. I found a service bulletin but a GM dealership said the bulletin info is no longer available. I repeated the same movement on my second Lesabre, 2003 LE with opposite results. The TCV shaft of the ’03 rotated smoothly and would stay in any position once released, that is 12, 1,2,3,4 o’clock position with no twisting effort needed.

Service Bulletin:
NHTSA ID: 10013102
TSB ID: 08262004

Any ideas? It'* getting cooler outside and I could use more engine heat and the noise is annoying.

As long as it freely rotates, there is nothing wrong with it......you need an actuator...