My heater blower will only run on high speed. what is the problem

Hey bro, it's an easy fix. You need a new blower motor resistor and harness. I had the same problem with mine. All you need are these parts. about 50$ Heres the link: http://gmpartsdirect.com/results.cfm?addtocart=1&addpartnumber=pk15218254&singlepart=1&partnumber=pk15218254

Mine too. I ran a new ground wire. Works fine now.