I've found a couple of posts here about blower fans that only operate on high speed, but the issue I'm having is the opposite. All of the fan speeds work except for the highest speed (really the only one that's useful :P )
Thinking the issue was the switch controlling the fan, I've already replaced the control module in the dash to no avail.
It's a '95 Chevy Blazer.
Any ideas on how to trouble shoot it?