air conditioning vents in the center of the dash?

The a/c should come out all 4 vents. The 2 on the sides and the center ones.

Here are the things that can cause it to be a tad warmer.

If your heater valve is not fully closed or that the valve is busted, then you will have heated air coming out of the center vents negating the effect of the a/c.

If your Defrost servo is malfunctioning then you are going to have defrost only and no air coming out of the center vents.

To check the heater valve look to the left of the brake booster there are 2 hoses coming out of the fire wall one has a valve on it. I would bet that it isn't fully shutting off, if you have air out of the center vents but it is "hot". you may have to adjust the cable or the slides in the control unit a tad.

If there is no air coming out of the center vents then you have a bad servo or a bad vacuum line.

To replace that servo you have to remove the dash there is no other way to get to it.

It is the same servo that is on the outside of the car opening and closing the fresh air vent.

Briano, thank you very, very much!
They do work and very well I might add!

It was the switch in the heater hose by the firewall.

I love this car!

Do u have to remove the dash to replace the defrost servo hose. I have been messing with it for a while and i want to see if its possible before i remove the dash. I am thinking that my hands are just to big and was going to get my daughter to give it a stab if it was at all possible

The only way to remove that right side of the heater box servo is to take the dash out. I am terribly sorry to inform you of that, but hey
All Cabriolet owners have been there, and I have been there 5 times in 3 cars. It is possible that your dash has been removed before and the screws that hold it to the knee bar are missing as they are a real bugger to get to.

Now at cabby-info.com there is a how do I remove the dash tutorial
http://cabby-info.com/Files/DashRemoval.pdf

For the un informed, the dash servo has a arm on it that is keyed to the flapper, but there are 2 fingers on the flapper arm that if you gently squeeze together they allow the arm to pop-off.

The dash servo is the same servo that is used for the fresh air/recirc air that is in the rain trray, and is good practice for the inner servo, as you can see the keyway etall. As a matter of fact if you go to a wrecking yard, they (the fresh air servo's that are metal seem to be better than the plastic ones. Ans can easily be removed.

How do I tell if the heater valve is busted? I'm having the same issue with the A/C only working well on the outside two vents on my '81 diesel Rabbit.

The center vents blow semi-cool air when the engine is cold, but after I drive for a while the air is pretty hot out of the vent. The heater valve in the engine compartment moves when I slide the temperature setting, so it seems to be working well.

Could dispersed heat from the engine compartment be heating up the duct work to the center vent? What else could be causing hot air to come out the center vents, especially as the engine warms up?

It isn't that the heater valve is moving, it is that it is allowing water to circulate when off.
Why is that happening? The heater valve cable isn't fully allowing it to the stop, or fully closed.

The heater valve even though it is off is not fully stopping the flow of water.
Heater valves get gummed up just like the rest of the system. The difference is that they made 2 types of heater valves over the years.
The original one is a flag type, that basically shuts off the flow to a trickle (yes it doesn't fully close) as there is a small hole left when closed, this allows for water to semi circulate, if it didn't then you could face a really corroded heater core, and that isn't a good thing.

The second type is like a ball stop, it too allows for a trickle. But that trickle is over come by the a/c.
Now, how can you get your a/c colder.
Proper charging of the system.
Your fresh/recirc valve must be functioning.
The recirc servo is in the rain tray infront of the fresh air plenum (duct). When the a/c slide switch is fully to the right, that tells the servo to engage, and to pull the door up. This shuts off air coming in across the hood and heated by the engine bay. It also tells the system that you can re-use the cooler cabin air. Cooling chilled air is better than chilling air coming off the hood. No it isn't going to get stale, as the cabby's aren't air tight any way.

Now I have only been driving these little guys since 1980, and have seen this issue for years. If you don't want to have water circulate in the system, then you have to by-pass the heater core. But then in the winter you would have to re-connect it.

I have placed a a/c cut out switch in my cars, so I can choose to run the a/c or not. If I want defrosted air with no a/c running I turn the a/c compressor off.

If your car is aged, then I would consider replacing the heater valve, on a cold car with 2 pinch clamps, it is a 10 minute job to replace it with a known good unit. Shoot the next time you are in a wrecking yard, take a minute to cut a used one out and look at it while you turn the valve.

They do break internally, and even thou the cable pulls the arm, the valve doesn't move.

When the car is parked in the sun, The plenum heats up. The air around the heater core gets hot, the heater core since it doesn't have colder air blowing over it warms up the surrounding plastic. When you get in your car to start it, you get cold air that can't compete with the pre-warmed box.
To compensate I usually turn the center vents off, and run with the side vents only for a few minutes. The side vents are colder as they don't run over the heater core. The air from the a/c will start to cool the air box down. Once it is cool about 5 minutes, the center vents should only be about 5 degrees different than the sides.

Now if you want to completely shut of the heater in the summer, then again the only way to do that is to place a by-pass on the hoses.

Thanks for the detailed post! I think I'll start with finding a working heater valve and replacing that. That would make sense that it isn't shutting off and so it is allowing too much water to circulate through the heater core, negating the effects of the a/c.

I checked the fresh/recirc valve and that guy is working just fine.

So because the side vents don't run over the heater core, they can't push hot air then? As I've been fiddling around with the heating and a/c systems I did notice that I couldn't get any hot air out of the side vents and was wondering if that was normal.

Hello to all, I have not visited the forum in quite a while because our 1985 cab has been running beautifully for a couple of years now thanks to all the help you gave me. Now on to the question.

From your earlier advice I replaced all of the vacuum lines about 3 years ago and the original R12 AC system is operational. We live in the Phoenix area so my wife likes that about now. Last summer however when she switched from heat to cool for the summer, cold air began blowing from the defroster vents up top reducing the flow through the other vents. Last weekend I went back through the vacuum system to make sure all was OK and replaced a few connector hoses but all was good. Now from other posts you talk about the defroster servo going bad and needing to remove the dash to replace it. I really don't want to do that so the big question is.... Is there any other way to force those defroster vents to close, either permanently or seasonally so that we can get all that cool air up front. Since we are in Phoenix, defrosters are rarely if ever needed an I would not care if they never worked again. Does anyone have any advice short of ripping out the dash?? Thanks for any information you can give. JK

Yes, use my how do I remove the center vent thread. You will see the air flapper.
Start your car and place the selectors in center vent, the flapper should pull if it doesn't then you have a bad servo, which you suspected already.
there aren't any real flapper vents, there is but one flapper that directs the air either out front by re-directing the air out the front or by staying closed it directs the air to the defrost. The default or rest setting of the servo is defrost.

With the flapper engaged to move, get a thin screw driver and "assist it" Then insert a piece of plastic or wood to keep it open. Reinstall your vents and Wally, you are done. There is a how to on how to add heat to the side vents, which I suspect that would be nice, but all in all, the servo needs to be replaced.

defrost/front servo in drawing


unedited:


Where you are inserting the pulls.