Does anyone know how the ducts work behind and under the dash. When I put my controls into defrost only or floor only, air still comes out other vents. I'm assuming as the truck gets older things don't work as they should.
Has anyone fooled around with this? I assume the ducts work on air pressure. Is there a pressure tank or valve that may be weak and needs to be replaced? Should I oil the axles on the vent doors? Is there a foam pad around the vents that needs to be replaced?
As an example. When I turn the AC and fan on full blast it really doesn't come out the face vents very good. When I replaced the blower motor I turned it on before putting the cover back on and it was like a wind tunnel but it's not the same coming out the vents.