I know, the site's search function sucks. Use Google instead with these search terms:
fan only runs on high site:gmtnation.com
Might have to narrow down your search terms. Is it the radiator fan or HVAC fan? Always use the "site:gmtnation.com" operator and you'll get results from here only.
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.
Another option is to put your search terms in double quotes, to search it as a single string, and not the individual key words. But it's best to keep the search phrases shorter, to get more hits on that string. The search engine here omits words shorter than 4 characters, as you saw..
Without the "site:" operator, even on DuckDuckGo, the results will be interspersed with just about anything and stuff not related, just like on Google. Using the site: operator will return results only from the site specified.