Question1995 s10 blazer 4.3 v6. The air & heat only blows out on the floor and defrost vents.I changed the control unit & still the sme
AnswerWtwt,
Your directional doors are all operated by a system of vaccuum lines. I am looking at your vaccuum diagram now.
The way it works...
Your vaccum source is connected to a vaccuum harness connector. As this connector receives the elecrical system that you send it by turning the switch, it changes which connector(s) get vaccuum pulled on it/them in order to open or close the desired doors.
Being that your floor and defrost vents are working, and the chart says they are in vac mode (versus vent) that tells me your source vaccuum is good. So, the problem lies in either your vaccuum harness connector not switching the ports as it should, or, the black or black/tan vaccuum line has a leak in it somewhere substantial enough to not allow any vac to get pulled, or what they call on here your center outlet duct actuator is faulty. This is just the actuator that turns the door itself. And this is also the next component that I would replace if you are changing parts in the hopes of fixing it. But the right way to do it would be to either use a handheld vaccuum pump (same kind you use under the hood with the squueze handle), disconnect the lines from the vaccuum harness connector, and pull a vaccum on each of the above two mentioned lines. If it closes the door as it should, I would replace your vaccuum harness connector itself.
In all honesty, this can tend to be an in-depth repair, on some vehicles it involves removing the dashboard, and unless you are confident in what you are doing, I would recommend taking it to a reputable shop to have them check it out.
Thank you for the question, hope I was of a little assistance. If you found this answer useful, please remember to rate this answer. If I can do anything further now or in the future, please do not hesitate to ask. Thank you again for the quesion and good luck in everything.
