My 2000 f150 5.4 heater blows cold air, no leaks, not running hot, cannot hear acuator door or motor so could be that,BUT, its running rough like it has a miss or a vacuum leak.

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your vehicle. If your F-150's heater is blowing cold air while the engine is running rough, there could be a vacuum leak or a problem with the heater control actuator. Since you're noticing a rough idle and lack of power, a vacuum leak may affect engine performance and the HVAC system. The heater control valve, which directs coolant to the heater core, relies on vacuum to actuate. Inspect all vacuum lines, especially around the intake manifold and heater control valve, as small cracks can cause these symptoms. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!