After not receiving a accurate response from the experts on this website, I
did my own research on this problem.  After many calls I finally talk to a
HVAC design engineer at Mitsubishi Motors.  According to Mitsubishi
Engineer, if the blower fan only operates on the highest speed setting, or
is missing one or more speed settings below that, most likely the blower
resistor has failed.  The part is not known as a blower resisitor in the
technical manuals.  It is known as a heater resistor.  The resistor is
located on a separate wire connection and mounted on the air exchange unit
with resistor half of the unit inside of the air exchange.

Your friend is correct , the resistor only resists voltage on speeds 1 2 and 3 , the 4th speed is 12 volts and hence no resistance.
The part is inexpensive and takes no more than 5 minutes to replace .

Apologies for not replying sooner .

Jeff
 The blower motor only runs when the dash control unit fan control is set on
 high.  All connections and the dash control unit has been replaced but
 blower only runs when set on high?  Is the blower motor going out or is
 there another control module that I am not aware of?