I have a 2003 F150 that has recently had a loud thump in the central dash area. It is associated with the temp control in the dash. Now my heater blower stays on when the key is off and as I am driving down the road I hear 5 tones coming from the drivers side lower dash. The tones will repeat for a few times and then stop. Any ideas on what could be causing this?? Any help is greatly appreciated.

 

With the description you gave about the only thing I could think of that would cause a loud thump in that area would be a control cable breaking loose. The fan remaining on after the key is turned off seems like it would have to be related to a short, possibly caused by the broken cable? You didn't tell us what the "tones" sound like so no clues there.