Ford Repair: 2001 Ford F-150 - Heating and Cooling Problem, ford f 150, vent area

Question
A while back my a/c stopped working and all I get is a constant flow of heat from the floor vents.  Even if I adjust the control to the cool air vent all I get is hot, hot air.  

Whether it's related or not, I'm not sure but a week ago there was a rattling/tapping noise that coming from the floor vent area.  For some reason I decided to try the a/c and it starting working again until I shut the truck off.  When I started it again, it was back to heat again.  I pulled the cover off the floor vent and noticed the tapping noise coming from a flat little white box-like component.  It was almost like a little motor trying to start but not quite getting there.  I unplugged it from what appeared to be it's power source and it stopped making noice.  However, still nothing but heat.  A friend said something about it being the heat door being stuck behind the dash.  Any help would be appreciated.  Thanks.

Answer
Most likely, the blend door actuator is what you unplugged-- it controls the air temperature and being made of plastic, it can break.  This can be an expensive repair, if the blend door itself is broken, the dash has to be removed to get a new one installed.  Shop around for the best estimate.