2005 New Blower Motor Resistor issues

I just installed a new blower motor resistor and blower motor in my truck because the AC was only working on high and sounded like trash (grinding). The AC sounds great now and blows hard but that’s the only issue.. it only blows hard, on all settings it’s the same speed. Any ideas why this might be happening? I did only replace the resistor and not the wiring harness because there was any apparent hot spots on the contacts.

 

Mine only worked in high speed as well, and upon researching read that the factory wire harness was the most common culprit of the issue...changed that out in my 2005 and resolved the issue