I've pulled the entire AC/Heater box apart trying to find a restriction in this system. All speeds work, but it doesn't seem to blow very hard. I have several GM trucks from 2003-2008, and they will blow the hat off my head. Is the 99 just that much weaker? It's like half the power of one of our newer trucks. I've made sure all air doors open and close properly. Evaporator core is clear on both sides. I don't want to spend $50-75 on a new blower motor unless I know that is the problem, or if there is a higher power motor out there, I'll get that.