I have heat on the passenger side but not the drivers, well it is luke warm, I had read that the coolant runs across the evaporator first then the heater core and if the 134a is not fully charged this could affect what is happening in my truck?

I have heat on the passenger side but not the drivers, well it is luke warm, I had read that the coolant runs across the evaporator first then the heater core and if the 134a is not fully charged this could affect what is happening in my truck?

What you describe sounds more like an air blend door isn't moving to the correct position.
More info about your vehicle will help:
https://www.askmehelpdesk.com/cars-trucks/when-asking-about-your-vehicle-303903.html