Have an 03 expedition the front heat works fine and rear blows cold. a month ago it was the opposite front was cold rear worked fine. Any ideas on what it could be blend door or something else? Also have a clicking sound coming from passenger side in the rear above the tire. Any ideas what it could be also. Thanks for any help?

 

The clicking that you hear is a stripped gear on the motor that opens and closes the blend door. Its about $50 from Ford.