Edd W

If the headlights are not aimed correctly this could be a sign of a faulty ride height sensor - but could of course, aslo be simply because the car hs bottomed out of the stops and is below the limits of the headlight adjustment range. I do not know if the headlight height setting is taken from the rear sensors or a combination of front and rear to pick the attitude of the car rather than simply rear load.

The other things you say sould like the compressor has failed - either that is the fault or there may be a leak or other fault causing the compressor to run for far too long.

mishar

By variance in air volume applied to the spring unit.

Edd W

But air is compressable so if you pump in more air to raise the ride height it will increase the pressure. Think of the spring as a bit like a tye - lower pressure (less air) and the tyre will deform more at the contact point. If it were a fluid based system I would agree, but they would by hydraulic rams not pneumatic springs and the ride would be solid.

mishar

Analogy with tires is not good. Tires have close to constant volume so pumping more air increases pressure not volume. Air springs are constructed so that they change volume. More air more volume. Pressure is changed only if load is changed. Check images in the mentioned document for construction details. Spring boot is small one inside larger protective boot.

AusA8

So I took my beloved, but severely nose down beauty into the dealership on Saturday.

Put a limit on their time to diagnose the issue. Within an hour, they rang me and said that the compressor is dead (we all knew that anyway). So I said, and what is the cause? Response.... A $35 part... The relay... The compressor failed trying to keep the car up.

What I wanna know is, what does this relay do and how would it cause an air leak to the fronts only?

Oh, and they wanted $4,080 AUD to fix it... Compressor is $3,140 AUD!! I'm still chasing suppliers for the OEM compressor and found a bloke in Germany on Ebay. He claims that they are OEM units, but I recall reading someone on here (simonbackman) or similar bought one of these units and had issues fitting it.

Thoughts on the relay and supply of new compressor?

Mister Bally

Best to buy a genuine WABCO electric air compressor. Look for the WABCO logo (all Capital letters) on the decal. There will also be a Teves / Continental logo as it is their air suspension system as far as the four struts/dampers and ECU (Electronic Control Unit). That logo is a scripted "Ate" for Alfred TEves. I have seen them on ebay as well as a google search.. Not sure how they sell them so cheap but who cares.

AusA8

Thanks Mister Bally, I'll look into them.

Any thoughts on the relay??

mishar

I don't see how any relay can cause air leek. Could be that they figured out that you do not plan to pay their crazy price and deliberately misled you. I think that it is best to install new compressor and than find a leek. VCDS would be of a great help. Anyways for that price you can buy all special tools and start your own business.

FlyTyinFool

...Or they're just shot-gunning the diagnosis. If you replace everything, it's bound to get fixed, right?

AusA8

I was afraid that you guys might say that about the relay... I've gotta go and have a chat about the car later this week so I'll ask specifically how the relay causes the leak.

Cheers