LHS heater too cool

I have a 96 LHS at idle the heat is cool, at 3-4000 rpm it warms up but not enough. Waterpump is fine, Thermostat is fine(new too) inlet flow to heater core is full but not gushing, flows out of core at approx same rate, I back flushed the core and saw a reasonably large glob of scum wash out, but flow through the core seems to be unrestricted now,still same problem,It there a heater control valve somewhere in this system? Is there a trick to bleeding all the air from this system other than the bleeder at the thermostat? Any Ideas? Thanks t.

I had a similar problem a few months ago. Blender Door Actuator was the problem. Good luck!

I had a similar problem a few months ago. Blender Door Actuator was the problem. Good luck!
Thanks for the info. I removed the center registers and can I see a door I turned the temp knob and can see it sweep from what appears to be fully open to fully closed. I tried to help it a little further when it stopped but it feels solid like it has moved all it should. Did this happen with your blend door problem or is there another door that I cant see that affects temp.I appreciate ant suggestions.Thanks T.

On my climate control unit there is a built in diagnostics program. I have a 97 Concorde, so yours might be similar or the same. Check out this site for more info http://www.allpar.com/fix/codes-climate.html

The door was just sticking on mine, but running the diag program told me the problem. It was the sounds like it was the same door that you found.