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Air Vents Trouble Shooting!!


Mar 8, 2006
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15 VE SSV 6.0t V8 A6 SEDAN
Hi guys. Thought id post this to help people out with anyone that has problems with the Vents changing to the Windscreen whilst accelerating or any other vent probs.

On my car, the air would come out of the Face Vents and when accelerating, would change to the Windscreen. Also if it was on Recirculate, it would change to Outside air as well. Very Annoying.
I Knew there was a leak somewhere. Went though all the usual checking all connections at the engine, the one way valve, all connections under the dash etc. ALL WAS OK. :bang:

I heard a slight HISSING Noise coming from under the D/Side Dash, and found that a Vacuum Air Mix Servo had the hissing sound. I decided to check the connection - was ok. I disconneced the Orange hose from it and blocked it. Suddenly, The noise was GONE. I Took the car for a test drive and Walla. The problem was gone. :thumbsup:

So if anyone is going through similar probs, try the following: Climate Control Models only: May be similar for Standard System but may need to remove the Dash Vent Selector and do the same thing there:

1. Remove the Glove compartment.
2. Remove the Upper Cover just behind the glove compartment (Has the footwell light on it).
3. You will see a Long Clearish Vacuum Connection that is pushed into a Long Black Plastic thingy (Vacuum Solenoid Block). Disconnect the Vacuum Train from it.
4. Connect a Small hose into each Hole of the Train (there are 2 on each block, only to the very top one, the other will leak).
5. Suck air with your mouth until you can suck no more, and Hold hose from loosing the suction. ie with your tongue.
6. Do this to each section. If an air mix servo is the problem, you will notice that it will either leak or you wont be able to reach maximum suction (ie you will keep sucking on the hose and it wont hold any suction.
7. If you find one that doesnt hold suction, take note of the color and find that servo that it connects to. (Located Under the Radio etc - Need to Remove Sides of Console to Gain access).
8. Try Disconnecting that colour from the servo unit and block the hose with something (I Used a Pen Lid.)
9. Road test the car and see if it works.
10. If it is the Air Servo Mixer, they are bastards to Replace because of there locations of the Screws. But with enough mucking around, you should be able to replace it.( A Short Screw Driver..... Very Short.)

Another thing it can be is the Vacuum Solenoid Block (As mentioned above). They have been known to leak and can cause erratic Vent probs. But you need to be sure that there are no leaks anywhere else otherwise you will just waste your money.

Prices for the Vacuum Servo's are around $90 from GMH (Ripp off) :cry:
Prices for Vacuum Solenoid Block are arount $90 from GMH as well.

It pays to do a bit of testing first before buying any parts.

Hope this helps out a few people.

I anyone else has suggestions feel free to post them. :)