replacing resistor on 2004 GMC Canyon

the heater blower switch only works on high how do u replace it and where is it located

Asked by for the 2004 GMC Canyon
NEXT TO BLOWER MOTOR. YES REPLACE IT ALSO CHECK PLUG FOR SIGNS OF HEAT
FROM BAD CONNECTION NEW PLUG AVAIL. FROM NAPA.
2 answers
MOUNTED IN HEATER BOX BUT REPL WIRE HARENESS ALSO