2000 LeSabre HVAC blend door?

I have a 2000 LeSabre that blows air conditioning out of the penger vents and warm air out of the drivers vents. The system was serviced and recharged at the end of last summer, so i know ru134 is not the issue. I also checked the pressure. Can someone please tell me what actuator i need to replace and perhaps give me a part number so i have some idea what to look for. I have manual climate controls, it is not the dual zone digital system.