1997 F-150 SUPERCAB,4.6, 4X4,XLT.SEEM TO HAVE PROBLEM WITH AIR COMING FROM HEATER AND A/C UNIT. WHEN I START THE TRUCK COLD WITH ALL THE SETTINGS ON FULL EVERYTHING WORKS WELL.BUT IF I CHANGE ANY OF THE CONTROLS NOT INCLUDING THE TEMP SETTING I LOSE ALL AIR FLOW AND CANNOT GET THEM BACK. HAS ANYONE HAD THE SAME PROBLEM AND IF SO HOW DID YOU FIX IT?