[MattPSU]

How hot is the engine getting? If there isn't much heat in the system, it's not going to put out much heat. When I lived in Pennsylvania, I had to put a piece of cardboard in front of my radiator in the winter so that my heater would blow hot air. Without it, it would just blow cold no matter how much it ran. It would only get warm when the truck was sitting still - when cold air wasn't being forced across the radiator, cooling the system. Might be worth a shot to just try putting a piece of cardboard between the radiator and the grill. Watch your engine temps, and don't forget to take it out when spring gets here. Good luck!