Blower motor speed?

Hello, I'm Danny.

A very common problem with this issue on Chevrolet trucks is the blower motor resistor. It was a design flaw and usually the electrical connector melts and causes this condition. If you check and see yours is melted a new harness assembly is readily available at auto parts stores under the Dorman brand name. I've attached picture steps below of its location and how to replace for your truck. Hope this helps and thanks for using 2CarPros.