I dont have any heat in my truck.

I am not sure if this vehicle has a heater control valve or a blend door inside the dash plenum. The heater control valve is the device that allows the hot water in to the heater core. You can find it by following the heater hoses from the heater core out. It is either controlled by a vacuum line or cable. The blend door is allows the air to be directed over the heater core, which heats it up. If you don't have a valve, then try making your heater/AC go from hot to cold to hot with the temperature control. See if you notice a change. If no change, or if you hear a clicking noise, then you may gave a defective blend door actuator or temp control. I hope that this info gives you some ideas.