The truck warms up real good, it will sweat you out of it. On the passenger side floor area, when going down the highway and it is cold out there is cold air coming in. Is there something I need to cover up or something missing? Could it be coming in from the fresh air area or vent???

 

could be a leaky door seal
could be the fresh air coming through the vents, what happens on recirculate?

 

I would say you have a bad actuator on your Blend Door or your temprature Door on the passenger side. These trucks always, always fail an actuator in the heater box. They are a bitch to get to and reasonable high priced pieces of crap. I see this typical repair in my shop all the time.

 

Its not door seals, they are new. So does the blend door allow cold air in from the outside then? I do not have the dual climate in this truck. So would I just need the blend door actuator, not the temperature actuator? Any part numbers? It seems this happens when i'm going down the highway, not around town. Is there anyway to check the actuator before I just throw money at it? Thanks