Heater fan only works on the high position?

Sounds like I a possible multifunction switch l

You can download the owners manual for your 2004 GMC Canyon from the following link.(http://www.extendedgmwarranty.com/owners-manual/gmc/2004-GMC-Canyon.pdf ).Your valuable feedback would be appreciated.Thanks for choosing Fixya.

TinuAlbinAlex

That is usually caused by the resistor module for fan motor speed control. Replacement is quick and not very costly

This is caused by a defective blower motor speed control resistor, the resisitor is located next to the blower motor.

It's your blower motor resister. It is located on or near the blower motor. This, when it goes bad, will cause your fan to only work on high.

powe windows do not work

Check the blower resistor pack - usually located in the heater air ducting in the blower fan airflow. Check for loose connections and open circuit resistors on the unit.
If speed 4 works always, its unlikely to be the blower motor ground connection.

Replaced connector and everything is perfect. Several canyons have had this same issue . looked through several forums. Thanks Guys

There is a fuse I would check first if you haven't tried that yet. They had problems with the switches in some of those vehicles. If you could take the control out and unpug then reattach the plug it may start working meaning the switch is bad.
You may have a bad fan motor. Do you have a test light to check for voltage at the motor itself?
Lastly, there is a resistor set that changes from low to high that may have one or more resistors burned out.
Dale

The Canyon has an inherint problem with the Fan Power cable being loose. When I say loose...I'm saying that you need to adjust the wires and then take a zip strip to tighten it up.

Passenger side under the dask are 2 cable hook ups. the one on the farthest right (Only 2 wires going to the plug) is the fan power cable. Jiggle it while the fan is on position number3 so you can hear when it comes on!!!