The blower motor and blower resistor have both been changed!!!

What is your question?

This is the second time changing the blower motor and blower resistor with parts bought from O'Reillys. I am unsure at this point if I need GM parts and if it would solve my problem. Currently in the mornings when starting my truck the fan will not kick in. After driving or letting the truck run for 10 minutes or more the fan will kick in and give me heat. It seems like with the colder temperatures this has become worse. I have replaced the blower motor, blower resistor, check for moisture, and I'm just puzzled.