Bought used 2010 F-150XL with 62,000 mi. and no fancy temp controls. Switches in dash pod change lights as to where air should be blowing but only blows out dash vents. Blower speeds are OK, temp control is OK and compressor comes on with D/F setting. Had same problem when bought used with 62,000 mi on it. Car dealer fixed it. Said they cleaned up the linkage. 1 year and 20,000 mi. later same problems and no used car warranty. Any clues where to start??

 

Stuck blend door or actuator.

 

Thank you.