I have an 04 Yukon XL. The Rear Heat is stuck in the ceiling position and will not switch to floor. It seems like I have an actuator that needs to be replaced but I can't figure out which one. Most of the threads I have seen refer to the Blend Door that controls AC/Heat Blending, not the ceiling to floor air direction, which I am having problems with. Also, I only see one actuator on the Parts Diagram which is the Hot/Cold Blend Door. Anyone else had this issue or can help me figure out the correct part number for the Ceiling/Floor actuator? Thanks!!

 

the actuator you're referring to is called a mode actuator, in this case probably auxiliary mode actuator

 

Thanks for the response! I found the HOT/COLD actuator and the Floor/Ceiling actuator are both AC Delco p/n 15-72972. Ended up having to replace both of them along with installing the updated control module 15-73506 to resolve all my issues. Got all 3 parts on Amazon for less than my dealer wanted for a single actuator.