Ford Focus: heater blower only works on high setting

I am aware of other post about the blower only working on high,but none of
the links work. I want to fix it myself,I think it is the thermal fuse.
Can someone please give me some working links or a description of what I
need to take out to get to it? I have a 2003 focus zts. Any help would be
appreciated. I can't use the a/c because it only works on the lower fan
settings and it has been in the 90s lately.

Dude, the reason the fan only works on high is because the resistor is
bad. Call the ford dealer, get the part -- like $10. It mounts under
the dash on the firewall on the passenger side. You won't likely find
it by looking at the system wiring -- just know that it is a flat
plastic piece, mounted by a screw or two I believe, with the plug into
it.
Best bet, buy the replacement first so you can recognize what it looks
like. Screwdriver, flashlight, $10, and like 10 minutes tops and
you're golden.