We are new Cabriolet owners and are living in the Phoenix area. It is summer and it is really really hot. The AC blows cold and is working well but it is only blowing from the two outer vents. It is also blowing some from the defroster vents up top so I am loosing some there. I have checked the dash controls and they are set to the correct positions and I have been inside the dash and worked with the control there as well to see if rotating it further would make a difference...it didint. I have new vaccum line coming this week and I will replace all of the vacuum lines I can get to.

Can someone tell me where to look for any information on how this AC vacuum, damper, venting, blower electrical stuff is supposed to work, or if you can walk me through some things to check that would be great too.

Thanks to all......Happy Hot Summer

This is a very common problem, it is repairable, but you have to remove the dash if the Vacuum lines all check out.

There is a Defroster Servo, that at rest is defrost (Rest means no vacuum).
When you place the selector on full frontal, the vacuum is applied to that servo and it pulls the
flapper down, and allows the air to go full frontal.

Here is the parts breakdown with that servo circled
http://i3.photobucket.com/albums/y65/briano1234/heater%20vent/heaterbox-2.jpg

It actually looks like:

http://i3.photobucket.com/albums/y65/briano1234/Dash/centerservo.jpg

It is on the right side of the heater box.

Now you can use a pencil and poke it open then hold it that way.

The center vent/defrost vent vacuum servo is most likely shot (common ailment). Nine times out of ten, that component is the problem.

The vent flap is located inside the dash, behind the center vent. When the selector is moved to any of the 4 left positions, vacuum is routed via the vacuum distributor to the center vent/defrost servo which in turn opens the vent flap; this closes off air to the defrost vents and diverts air out of the center vent.

For more HVAC information and instructions on removing the dash (which you will have to do), go to www.cabby-info.com .

Thanks guys for your responses to my AC question. I think I have it fixed. I got away pretty lucky on this one. I bought about 8 feet of new vacuum hose and black tubing and replaced all of my vacuum lines and like magic it was fixed. it took about 10 minutes and a few bucks for the tubing. I must have had some plugged lines so now everything is good. Can anyone tell me however what that purpose of the goofy tennis ball vauum reservoir is on the underside of the hood is? The vacuum line running into it was just flopping around inside because the grommet had melted away so it was no longer sealed. The AC venting system still seemed to work fine without it being sealed Any ideas on that?

That is also called the Egg Crate, I call them Rabbit Balls, and have painted mine GOLD.
They keep the vacuum present under acceleration, as if they weren't there every time you accelerated your car the full frontal would go to full defrost and back.

Very COOOOOL ( AC Question ya know) I found the correct sized grommet at Lowes and reintalled it all tight and sealed so we will see if does what it is supposed to do.

Thanks to all for your help to a new Cabriolet owner

See ya

The actual name for the "balls" is vacuum reservoir. It is, in fact, the very first question on the HVAC page at the aforementioned www.cabby-info.com . ;)

You can try to find the proper-sized grommet, or just silicone it in place like I did.