AC Htr Not Blowing Air

[fivevs]

I've got a 98 Winstar.I've had problems with it before and have gotten some great advice on this website.My new dilemma is that whemn I turn the AC/HTR on, the air only comes out of the front window vents. It come s out either hot or cold, but only from those vents at the end of the upper part of dashboard that you normally use for defrosting the front window.I also noticed that my back A/C unit blows out hot air all the tme and only from the bottm rear vent. Any and all help would be appreciated. Thanks

[wiswind]

I do not have a rear unit, so I cannot be of much help there.....
The Front unit uses vaccum from the engine to move the air to the location that you select on the dash.
The default position, if there is no vaccum, is defrost, the position that you say it is in.
If you look up under the dash, behind the glove box, you will be able to see the actuator for the airflow selection.

On my '96 3.8L, the source of the vaccum is on the back, passenger side of the upper intake manifold.
It goes from there to a resevoir "box" that is mounted on the passenger side, next to the top of the strut.
Then a vaccum line goes through the firewall, into the passenger compartment.
You might try checking to see if you have vaccum in the lines, and if not, look for a leak, or pinched, or melted, etc vaccum line.
This is best done with the engine at idle......so you will be able to hear the hiss when you are checking.

This is different from the blend door, which has an electric motor, and serves to determine how much air travels over the heater core.......and connects to the temperature select on the dash board.

[Bensgirl]

I have a 2001 and just noticed I have the same problem too. Is this an exspensive thing to fix?

[fivevs]

On my unit I finally found the problem with it.There is small vacuum line which goes from the engine and through the firewall(back side of the engine if standing in front of the vehicle).Anyhow that tube goes to the back side of the switch (on your dashboard and below the radio)which regulates where the air flow comes from when you turn the unit on. On mine there was a small vacuum leak there which did not allow the actuators to open and close properly which in turn affects the ability to get the air flowing out of the front and lower vents.