I've noticed that when I turn my heater on, there is a burning rubber smell, or another way to describe it is a "hot brake" smell in the cab. My truck is new. Could it just be the "new truck smell" coming from the vents when the heater gets really hot? If anyone has had this experience please reply.

 

I assume that your heater is getting quite warm as it is winter time. I wouldn't worry about it at this point, its probably just glues and coatings from production. If it continues, take it to your dealer for a warranty claim.

 

I'm not sure on the design of the Ford heaters.

Vdubs run hot coolant through the passenger compartment heater core all the time and vary the cold air flow through the heater core by a large flap to adjust the amount of hot air.

The older vehicles used a valve in the heater hose to regulate the flow of coolant to the heater core.

If you get a burning smell with a constant coolant flow type of heater core then I'd have it checked out for sure, perhaps some assembly dummy forgot a loose piece of foam or something in the heater core box and it's melted it?