I tried that already, didn't find what I was looking for.
It's the HVAC blower motor. I know the SOP, I was just looking for anything I might not already know.
After doing a search for "how to change the blower motor resistor on a 2004 gmc envoy" to make sure it was where I expected it to be, I actually got some results leading to relevant posts here.
Forum engines need to stop removing words they don't like from our searches.
