Well, I had this problem a couple of years ago, before
the recall for the heater blower resistor. The connector
to the resistor is a bit cheap, and it melted down, taking
with it 4 or 5 inches of the connected wire harness. The
dealer was no help, so I patched into the wire harness and
built another connector. It's worked fine since.
Later, I got the recall notice from Ford, and I still get
them from time to time. And yes, it still burns me up.
The resistor is located near where the front passenger's
left foot would be, in the duct for the heat/air. It should
be easy to spot due to probable heat damage.
