My blower fan only has high speed on my 2004 gmc sierra. what is the location of resistor so I can replace

Most likely is your temperature control panel.These go bad often.But is relatively easy to replace. But if you are unclear of what I am talking about it's the panel that has the knobs on it that controls the fan.

High speed on the blower fan does not work thru the resistor.
There is a seperate circuit that sould feed 12 volts directly to the motor. If you have access to a schematic it would help.
The connectors for the high speed, burn out a lot. If you cant find I could look it up.

This condition is caused by a defective blower motor speed control resistor. The resistor is located right next to the blower motor with the connector end sticking out of the ducting for the AC/Heater system. Very easy to replace and the part is cheap as well.

The blower motor resistor is located within a foot of the blower motor in the duct that the blower motor blows into. The resistor is actually cooled off by the blower motor blowing across it. It has a wire harness that connects it to motor & fan switch. It is held in place by 2-4 retaining screws. Disconnect wire harness,unscrew retaining screws then lift out. Reverse order to install.

get a voltmeter; check for 12vdc at the blower motor with the blower turned on; if there is voltage, the blower motor is bad; should be located behind a panel underneath the dash on the passenger side; if the fan works on 1 or 2 speeds, it is probably the blower resistor located in the same area as the blower; u can check utube for details

The switch or the wire harness at the blower motor has gone bad. The highest setting 5 has no resistor, so the blower runs on high but the high current flow ends up burning up the switch's contact on that setting or the resistor wire harness at the blower motor has gone bad. Common would be the switch it self, if the switch is good. Then it's going to be the wire leads at the speed resistor by the blower motor under the glove box by the passenger leg compartment. Keep me posted, be glad to help you get your Sierra running 100% again soon.

more than likely yes the resistor

probably a bad resisiter in the plenum

Your blower moter is under your glovebox and very easy to replace.I dont think thats your ploblem.I would pull off the dash.It will snap right off without breaking anything.Then pull out the part that holds the selector switch for the fan speed.Then you unplug that switch.Clean the copper contacts.Plug it back in.If everything works again like it should and did in my truck then it is either that switch that is bad or the wiring harness.I would replace that switch.

There is a resistor attached to the blower box. Replace the blower resistor and this should solve your problem