'97 Riviera A/C Problems

My '97 Riviera A/C blows cold at times and other times only slightly cool, also, seems the retangular registers below the radio only blow warm as do the 2 round registers on the drivers door. Anyone have this problem and can suggest a fix?

i have that problem and its due to an actuator door stuck 1/2 way btwn cold and hot. http://www.regalgs.org/forum/viewtopic.php?t=26708