1998 f150 5.4 owned since new. 203,000. No heat at all. I've looked in the forums and have checked my switch, actuator, and blend door. All work just fine. Truck heats up normally and never overheats. The truck is full of coolent. Any ideas?

 

if you actually saw the blend door move I would flush the heater core. then point the truck nose uphill or just use a jack. then remove coolant cap and run with the heater on hot and the fan on high.

 

Did you bother checking the coolant hoses to/from the heater core to see if you have hot coolant flowing?

 

thermostat stuck open?

 

Thanks guys, ya I know the blend door moves because I opened the box and felt it move. I'll try flushing.

 

Do the simple test in post #3. That way, you'll KNOW what to look for instead of just guessing.