blend door
 

I have a 2010 Mustang. I would like to know the name of the part that controls the mix of hot and cold air. I have hot air coming out of vents when it gets hot outside. Is it the HVAC air door actuator? Is there a part number I could ask for? Thank you!!

Do you hear a clicking sound when you change the controls? If so, then it is more likely the actuators like you think. I had to replace the same actuator twice on my 2011. I got the replacements at Rockauto.com. Here's the link:

https://www.rockauto.com/catalog/mor...php?pk=3103092

Part #AR3Z19E616E

Hope this helps :)