Jetta air diffuser - how it works

[spiff]

Post #4 is a shortened version of my problem.
Post #13 is a video.
Hi Jetta owners and all,

I wonder if you can test this in your cars and tell me if I'm right or wrong.

I have the climatronic in my Jetta and I usually have all vents fully open, the air-recycle on automatic (it's the one with the A next to it). Sometimes with air-conditioning; sometimes without. In these scenarios, the air flow is approximately 90% to the air diffuser/10% to the front centre vents (not concerned about side vents atm. They seem to go at full strength).

Now, when I push the button for air to blow from the front, air stops flowing to the diffuser and it's 100% to the front centre vents. When it's deactivated, the majority of air flow goes back to the diffuser (90/10 approx).

Is this the way it works in your Jetta?

I recently sent my car for some audio install where they needed access to the diffuser and things have now changed. The air blows all the time through the diffuser and if I activate the front blower button, there's no visible change. It continues to blow through the diffuser. My dealership had a looked by they say it's installed right.

They tell me that if I want the air to come to the front centre vents, I have to manually close the diffuser vents. I don't think this is how it worked. When we had a look at a 2nd hand Jetta with a diffuser (not sure if it was climatronic. It didn't have auto-air-recycle and had Econ instead of A/C, but I don't think that makes a difference), it seemed to also only blow from the diffuser.

If that's the case, the logic of having the front blower button seems pointless.

Help? I'm not sure if it could have been affected by any electrics (motor? relays? controllers? servos?). The audio shop doesn't know either, so they sent it to the dealer to be checked.

[edit] The first time the audio shop returned it to me, everything was blowing through the front 100%. When I told them, they tinkered and it worked like I think it should. When they had to fix extra stuff [different subcontractor], it went to being 100% through diffuser. The problem is, they don't know what they did/didn't do that would cause this. They and the VW dealer said everything that's meant to be connected looks like it should be. They used a couple of other Jettas for comparison. I'm thinking it may not be the physical parts, but the connection or something else. If I can verify how the diffuser works, they can look into this further and I can pursue it further with confidence. Seems like the enthusiasts know more. [/edit]

This is what my default looks like.

[Maverick]

There is a flap that opens to divert air to the diffuser operated by the knob on top. The buttons to divert air to the windscreen vents, foot vents and front vents do use electronically activated flaps. All Jetta's and Golfs with the diffuser have climatronic.

When you operate the diffuser using the knob you should feel/hear a flap moving (do it fast and you'll definitely hear it). Most likely the guys that pulled the diffuser out have screwed up and it's stuck in one position and will need to be pulled off again, fixed and refitted.

[spiff]

Mav, when you say activated by the knob on top, is that the one where you manually roll to open/shut the vent?

If so, I do hear it opening and closing with a slight thud.

I can open and close it with no problems. My problem is whether it's open or not, pressing the 'forward facing button' to direct air flow at your face does nothing. Air just keeps going to the diffuser only. The only way to get it to the front is to turn the knob to shut the diffuser. This means the electronically controlled flap is the problem right?

[spiff]

Anyone else with a Jetta?

Summary if you didn't like reading the first post:

-Diffuser vent open, Front vents open.
- No buttons activated. Air flow is at diffuser.
- Activate forward airflow button and air flow moves from diffuser to front air vents.
- Deactivate forward airflow button and air flow moves back to diffuser.

Does it work like this in your Jetta?
Currently, mine works like this and I think it's broken because that's not how it used to be before an audio shop worked on it.

- Diffuser vent open, Front vents open.
- No buttons activated. Air flow is at diffuser.
- Activate forward airflow button and air flow remains at diffuser.
- Deactivate forward airflow button and air flow remains to diffuser.

The forward airflow button does nothing, it seems. VW said this is correct and I have to manually close the diffuser vent.
I want to know how it works in your Jetta. Thanks

[wokwn]

Use VCDS and perform the output tests. You can then watch the measuring blocks for the flap motors.

[spiff]

Use VCDS and perform the output tests. You can then watch the measuring blocks for the flap motors.

I'm unfamiliar with the process although I know what VCDS is. Can you please explain this a little more? I will have to try and find access to a VCDS here or take it back to the dealer. If I do that, I may have to explain in detail what to look out for. Any more information will be useful. Thanks.

btw output test = autoscan?

Funny thing is when I press the forward facing button, I can vaguely hear a change in airflow (like I used to), I just can't feel any noticable difference. It still keeps coming through the diffuser.

[Buckets]

Hey Spiff,

Just checked mine to confirm....seems yours is the same as mine.

As long as the diffuser is closed and no buttons activated, the air comes through at face level as well as the other vents. From what I can gather if the "face" button is activated this means the "face" vents and diffuser are active while the others are de-activated. This would mean the air flow depends on the diffuser position. Diffuser closed, air to the front vents....diffuser open air flow takes path of least resistance which is out the diffuser.

So either they're both right OR both wrong!

[spiff]

Thanks so much Buckets. I'm still trying to find more Jetta users who can verify the operation, and still reading up on various sites and forums.

You mention other vents being deactivated if the face vent and diffuser are active. Do you mean the side vents, top vent, bottom vents and rear vents? I think my top/bottom vents are off, but the side vents and rear vents are going all the time.

What I find odd though is, if this is the way it works, then what is the point of the face/front vent button? I'm almost certain that it's not how it's meant to work because of how I remember it working last time.

I'm going to try and see if I make a video (since this new bulletin upgrade now lets us do it) to highlight this.

[Von Richthofen]

Just checked mine...... It's the same as Buckets

[spiff]

Von Richthofen & Buckets,

What happens when the diffuser is closed and your 'face vent' button is deactivated. Where does the air flow to? Does it still come out of the face (two centre) vents? Does it also come out the side vents?

[Von Richthofen]

Yes the air flow comes out of all 4 dash mounted vents when the diffuser is in the "0" position.

[Buckets]

Will check mine in the morning.

[spiff]

Here's a quick video of the problem.
This shows how it is now - front button doesn't do anything different.
Note video annotation: The paper I used was too light so it shows the front blowing at full strength.
It's actually blowing at 90% diffuser/10% front.

At 0:02 is where it should be different. It used to be that the diffuser stops and the front blows at full strength when the button is on.
You can actually hear the difference in sound.

[Von Richthofen]

I don't think you have any problem...... Mine is the same.

The two centre air vents & the diffuser are one & the same output. It just depends on where you have the rollers set.

The default for the air flow if no buttons are pushed is via these & the two outer vents.

The button for face level air flow can be used with any of the other combinations. Therefore, I only ever use it when I want to modify the air flow when using the floor or demister air flow buttons. eg If I wanted hot air from both the floor vents & the face vents I would push both of these buttons.

[spiff]

Thanks for that reply Von Richthofen.
Somehow, I still think that mine isn't working right because I've (not once, but twice) had it working properly.
If what you describe is true, and your diffuser and front vents are open, then the face level air flow button does nothing.
The diffuser's purpose is to stop air blasting at your face, so if the face level air flow button is not activated, it should be going to the diffuser (is that how yours works?)
And if the face air flow button is activated, then it should come to the front vents (but mine just keeps going to the diffuser).

If I use footwell + front, it will go to footwell + diffuser unless I manually shut off the rollers on the diffuser. I didn't need to do that before.

I'm half tempted to take the diffuser apart and muck around with it, or speak to the audio shop guys and get them to tinker until they get it right.