04 sierra only the high setting(5) will work when I turn the fan on. Is there a relay/ fuse I can change or do I need to take this to the dealer to have it diagnosed?

Any help is appreciated.

Typically, when only high speed works, the resistor pack is bad. It looks like this http://198.208.187.182/internet/PartImage.jsp?mfgname=ACDELCO&prodlinecd=15&acpartnbr=15-81086 and will be located near the blower motor. Sometimes, the glove box needs to be removed to get at it.

//2000CAYukon