From my experience, with my 2005 Colorado: I pulled the glove box, and remove the Blower Resistor, by removing two bolts. Usually looking at the connector number#3 pin is burned. The resistor can be purchased at any GM Dealer for about $20.00 includes Tax. I Finally got tired of replacing the Resistor over several years. I purchased a Resistor and the wire harness from GMPARTSDIRECT.com! They will also tell you that they don't have a telephone #, that is too keep their cost down, (Flo Chevrolet Greensboro/Winston Salem North Carolina). The total cost approx. : $54.00 for both the resistor/wire harness.