Heater blowing cold air

I have done those same procedures on my 2002 Ford Taurus, plus I also replaced the blend door actuator, which I would suggest replacing. In my case, that did not fix my no heat problem, so it all adds up to the actual blend door/plenum chamber that moves in order to release hot or cold air. But my best bet for now is that it is your blend door actuator.

Just my two cents though. Hope it helps!

Here is the actuator for your truck on Autozone.

I do not know what exact engine you have or if it is P/U (Pickup) or SUB (Suburban), but I am sure this part would fit both regardless.

Thanks for the ideas. I will try getting the actuator next Friday and it a 4.3 l v6 two wheel drive pickup.

No problem, I hope it helps, and let me know! I checked the part again with the information you gave me and it is a fit. I guess it does not matter what engine it is, V6, V8, whatever. But I have posted another screenshot of the blend door actuator, same brand (Dorman), and much cheaper. So I would suggest just buying that one.

Here is a link to the actual replacement procedure:

https://www.2carpros.com/articles/replace-blend-door-motor

Thank you for all of this it will make the process much easier and I will let you know next week if it works.